Random access backoff indicator

ABSTRACT

A wireless device transmits, for a random access procedure, a first preamble via a cell comprising a first sub-band and a second sub-band. The wireless device receives a random access response. The random access response indicates a first backoff indicator indicating a first backoff time interval of the first sub-band. The random access response indicates a second backoff indicator indicating a second backoff time interval of the second sub-band. The wireless device determines a preamble retransmission for the random access procedure. The wireless device selects, as a backoff time interval, a shorter one of the first backoff time interval and the second backoff time interval. The wireless device performs, at a time based on the backoff time interval, a listen-before-talk procedure.

This application claims the benefit of U.S. Provisional Application No.62/790,400, filed Jan. 9, 2019, which is hereby incorporated byreference in their entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosureare described herein with reference to the drawings.

FIG. 1 is a diagram of an example RAN architecture as per an aspect ofan embodiment of the present disclosure.

FIG. 2A is a diagram of an example user plane protocol stack as per anaspect of an embodiment of the present disclosure.

FIG. 2B is a diagram of an example control plane protocol stack as peran aspect of an embodiment of the present disclosure.

FIG. 3 is a diagram of an example wireless device and two base stationsas per an aspect of an embodiment of the present disclosure.

FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure.

FIG. 5A is a diagram of an example uplink channel mapping and exampleuplink physical signals as per an aspect of an embodiment of the presentdisclosure.

FIG. 5B is a diagram of an example downlink channel mapping and exampledownlink physical signals as per an aspect of an embodiment of thepresent disclosure.

FIG. 6 is a diagram depicting an example frame structure as per anaspect of an embodiment of the present disclosure.

FIG. 7A and FIG. 7B are diagrams depicting example sets of OFDMsubcarriers as per an aspect of an embodiment of the present disclosure.

FIG. 8 is a diagram depicting example OFDM radio resources as per anaspect of an embodiment of the present disclosure.

FIG. 9A is a diagram depicting an example CSI-RS and/or SS blocktransmission in a multi-beam system.

FIG. 9B is a diagram depicting an example downlink beam managementprocedure as per an aspect of an embodiment of the present disclosure.

FIG. 10 is an example diagram of configured BWPs as per an aspect of anembodiment of the present disclosure.

FIG. 11A, and FIG. 11B are diagrams of an example multi connectivity asper an aspect of an embodiment of the present disclosure.

FIG. 12 is a diagram of an example random access procedure as per anaspect of an embodiment of the present disclosure.

FIG. 13 is a structure of example MAC entities as per an aspect of anembodiment of the present disclosure.

FIG. 14 is a diagram of an example RAN architecture as per an aspect ofan embodiment of the present disclosure.

FIG. 15 is a diagram of example RRC states as per an aspect of anembodiment of the present disclosure.

FIG. 16 is an example of a two-step RA procedure as per an aspect of anembodiment of the present disclosure.

FIG. 17A, FIG. 17B, and FIG. 17C are examples of radio resourceallocations of a PRACH resource and one or more associated UL radioresources as per an aspect of an embodiment of the present disclosure.

FIG. 18 shows an example of ra-ssb-OccasionMaskIndex values as per anaspect of an embodiment of the present disclosure.

FIG. 19A, FIG. 19B, and FIG. 19C are respectively examples of an RAR, aMAC subheader with backoff indicator, and a MAC subheader with RAPID asper an aspect of an embodiment of the present disclosure.

FIG. 20 is an example of one of MAC RAR formats

FIG. 21 is an example RAR format as per an aspect of an embodiment ofthe present disclosure.

FIG. 22A and FIG. 22B are example RAR formats as per an aspect of anembodiment of the present disclosure.

FIG. 23 is an example of a coverage of a cell configured with a DL andtwo ULs as per an aspect of an embodiment of the present disclosure.

FIG. 24 is an example diagram of contention based and contention-freerandom access procedures with LBT as per an aspect of an embodiment ofthe present disclosure.

FIG. 25 is an example diagram of a two-step RA procedure with LBT as peran aspect of an embodiment of the present disclosure.

FIG. 26 is an example of radio resource allocation for a two-step RAprocedure as per an aspect of an embodiment of the present disclosure.

FIG. 27 is an example of one or more LBTs performed for a two-step RAprocedure as per an aspect of an embodiment of the present disclosure.

FIG. 28A and FIG. 28B are examples of one or more LBTs performed for atwo-step RA procedure in an unlicensed band as per an aspect of anembodiment of the present disclosure.

FIG. 29 is an example of one or more PRACH occasion configurations asper an aspect of an embodiment of the present disclosure.

FIG. 30 is an example of one or more PRACH occasion configurations asper an aspect of an embodiment of the present disclosure.

FIG. 31 is an example of one or more numerologies as per an aspect of anembodiment of the present disclosure.

FIG. 32 is an example of backoff parameter values as per an aspect of anembodiment of the present disclosure.

FIG. 33 is an example of one or more preamble transmission opportunitiesas per an aspect of an embodiment of the present disclosure.

FIG. 34A, FIG. 34B, FIG. 34C, FIG. 34D, and FIG. 34E are examples of aMAC subPDU (or an RAR) as per an aspect of an embodiment of the presentdisclosure.

FIG. 35 is an example of one or more preamble transmissions with one ormore backoff times as per an aspect of an embodiment of the presentdisclosure.

FIG. 36A and FIG. 36B are examples of one or more preamble transmissionswith one or more backoff times as per an aspect of an embodiment of thepresent disclosure.

FIG. 37 is an example of one or more LBTs performed with one or morebackoff times as per an aspect of an embodiment of the presentdisclosure.

FIG. 38 is an example of a single BI as per an aspect of an embodimentof the present disclosure.

FIG. 39 as per an aspect of an embodiment of the present disclosure

FIG. 40 is an example flowchart of a base station as per an aspect of anembodiment of the present disclosure.

FIG. 41 is an example flowchart of a wireless device as per an aspect ofan embodiment of the present disclosure.

FIG. 42 is an example flowchart of a wireless device as per an aspect ofan embodiment of the present disclosure.

FIG. 43 is an example flowchart of a base station as per an aspect of anembodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present disclosure enable operation of randomaccess. Embodiments of the technology disclosed herein may be employedin the technical field of multicarrier communication systems. Moreparticularly, the embodiments of the technology disclosed herein mayrelate to one or more random access procedures in multicarriercommunication systems.

The following Acronyms are used throughout the present disclosure:

3GPP 3rd Generation Partnership Project

5GC 5G Core Network

ACK Acknowledgement

AMF Access and Mobility Management Function

ARQ Automatic Repeat Request

AS Access Stratum

ASIC Application-Specific Integrated Circuit

BA Bandwidth Adaptation

BCCH Broadcast Control Channel

BCH Broadcast Channel

BPSK Binary Phase Shift Keying

BWP Bandwidth Part

CA Carrier Aggregation

CC Component Carrier

CCCH Common Control CHannel

CDMA Code Division Multiple Access

CN Core Network

CP Cyclic Prefix

CP-OFDM Cyclic Prefix-Orthogonal Frequency Division Multiplex

C-RNTI Cell-Radio Network Temporary Identifier

CS Configured Scheduling

CSI Channel State Information

CSI-RS Channel State Information-Reference Signal

CQI Channel Quality Indicator

CSS Common Search Space

CU Central Unit

DC Dual Connectivity

DCCH Dedicated Control CHannel

DCI Downlink Control Information

DL Downlink

DL-SCH Downlink Shared CHannel

DM-RS DeModulation Reference Signal

DRB Data Radio Bearer

DRX Discontinuous Reception

DTCH Dedicated Traffic CHannel

DU Distributed Unit

EPC Evolved Packet Core

E-UTRA Evolved UMTS Terrestrial Radio Access

E-UTRAN Evolved-Universal Terrestrial Radio Access Network

FDD Frequency Division Duplex

FPGA Field Programmable Gate Arrays

F1-C F1-Control plane

F1-U F1-User plane

gNB next generation Node B

HARQ Hybrid Automatic Repeat reQuest

HDL Hardware Description Languages

IE Information Element

IP Internet Protocol

LCID Logical Channel IDentifier

LTE Long Term Evolution

MAC Media Access Control

MCG Master Cell Group

MCS Modulation and Coding Scheme

MeNB Master evolved Node B

MIB Master Information Block

MME Mobility Management Entity

MN Master Node

NACK Negative Acknowledgement

NAS Non-Access Stratum

NG CP Next Generation Control Plane

NGC Next Generation Core

NG-C NG-Control plane

ng-eNB next generation evolved Node B

NG-U NG-User plane

NR New Radio

NR MAC New Radio MAC

NR PDCP New Radio PDCP

NR PHY New Radio PHYsical

NR RLC New Radio RLC

NR RRC New Radio RRC

NSSAI Network Slice Selection Assistance Information

O&M Operation and Maintenance

OFDM Orthogonal Frequency Division Multiplexing

PBCH Physical Broadcast CHannel

PCC Primary Component Carrier

PCCH Paging Control CHannel

PCell Primary Cell

PCH Paging CHannel

PDCCH Physical Downlink Control CHannel

PDCP Packet Data Convergence Protocol

PDSCH Physical Downlink Shared CHannel

PDU Protocol Data Unit

PHICH Physical HARQ Indicator CHannel

PHY PHYsical

PLMN Public Land Mobile Network

PMI Precoding Matrix Indicator

PRACH Physical Random Access CHannel

PRB Physical Resource Block

PSCell Primary Secondary Cell

PSS Primary Synchronization Signal

pTAG primary Timing Advance Group

PT-RS Phase Tracking Reference Signal

PUCCH Physical Uplink Control CHannel

PUSCH Physical Uplink Shared CHannel

QAM Quadrature Amplitude Modulation

QFI Quality of Service Indicator

QoS Quality of Service

QPSK Quadrature Phase Shift Keying

RA Random Access

RACH Random Access CHannel

RAN Radio Access Network

RAT Radio Access Technology

RA-RNTI Random Access-Radio Network Temporary Identifier

RB Resource Blocks

RBG Resource Block Groups

RI Rank Indicator

RLC Radio Link Control

RRC Radio Resource Control

RS Reference Signal

RSRP Reference Signal Received Power

SCC Secondary Component Carrier

SCell Secondary Cell

SCG Secondary Cell Group

SC-FDMA Single Carrier-Frequency Division Multiple Access

SDAP Service Data Adaptation Protocol

SDU Service Data Unit

SeNB Secondary evolved Node B

SFN System Frame Number

S-GW Serving GateWay

SI System Information

SIB System Information Block

SMF Session Management Function

SN Secondary Node

SpCell Special Cell

SRB Signaling Radio Bearer

SRS Sounding Reference Signal

SS Synchronization Signal

SSS Secondary Synchronization Signal

sTAG secondary Timing Advance Group

TA Timing Advance

TAG Timing Advance Group

TAI Tracking Area Identifier

TAT Time Alignment Timer

TB Transport Block

TC-RNTI Temporary Cell-Radio Network Temporary Identifier

TDD Time Division Duplex

TDMA Time Division Multiple Access

TTI Transmission Time Interval

UCI Uplink Control Information

UE User Equipment

UL Uplink

UL-SCH Uplink Shared CHannel

UPF User Plane Function

UPGW User Plane Gateway

VHDL VHSIC Hardware Description Language

Xn-C Xn-Control plane

Xn-U Xn-User plane

Example embodiments of the disclosure may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may comprise, but are not limited to: CodeDivision Multiple Access (CDMA), Orthogonal Frequency Division MultipleAccess (OFDMA), Time Division Multiple Access (TDMA), Wavelettechnologies, and/or the like. Hybrid transmission mechanisms such asTDMA/CDMA, and OFDM/CDMA may also be employed. Various modulationschemes may be applied for signal transmission in the physical layer.Examples of modulation schemes comprise, but are not limited to: phase,amplitude, code, a combination of these, and/or the like. An exampleradio transmission method may implement Quadrature Amplitude Modulation(QAM) using Binary Phase Shift Keying (BPSK), Quadrature Phase ShiftKeying (QPSK), 16-QAM, 64-QAM, 256-QAM, and/or the like. Physical radiotransmission may be enhanced by dynamically or semi-dynamically changingthe modulation and coding scheme depending on transmission requirementsand radio conditions.

FIG. 1 is an example Radio Access Network (RAN) architecture as per anaspect of an embodiment of the present disclosure. As illustrated inthis example, a RAN node may be a next generation Node B (gNB) (e.g.120A, 120B) providing New Radio (NR) user plane and control planeprotocol terminations towards a first wireless device (e.g. 110A). In anexample, a RAN node may be a next generation evolved Node B (ng-eNB)(e.g. 124A, 124B), providing Evolved UMTS Terrestrial Radio Access(E-UTRA) user plane and control plane protocol terminations towards asecond wireless device (e.g. 110B). The first wireless device maycommunicate with a gNB over a Uu interface. The second wireless devicemay communicate with a ng-eNB over a Uu interface. In this disclosure,wireless device 110A and 110B are structurally similar to wirelessdevice 110. Base stations 120A and/or 120B may be structurally similarlyto base station 120. Base station 120 may comprise at least one of a gNB(e.g. 122A and/or 122B), ng-eNB (e.g. 124A and/or 124B), and or thelike.

A gNB or an ng-eNB may host functions such as: radio resource managementand scheduling, IP header compression, encryption and integrityprotection of data, selection of Access and Mobility Management Function(AMF) at User Equipment (UE) attachment, routing of user plane andcontrol plane data, connection setup and release, scheduling andtransmission of paging messages (originated from the AMF), schedulingand transmission of system broadcast information (originated from theAMF or Operation and Maintenance (O&M)), measurement and measurementreporting configuration, transport level packet marking in the uplink,session management, support of network slicing, Quality of Service (QoS)flow management and mapping to data radio bearers, support of UEs inRRC_INACTIVE state, distribution function for Non-Access Stratum (NAS)messages, RAN sharing, and dual connectivity or tight interworkingbetween NR and E-UTRA.

In an example, one or more gNBs and/or one or more ng-eNBs may beinterconnected with each other by means of Xn interface. A gNB or anng-eNB may be connected by means of NG interfaces to 5G Core Network(5GC). In an example, 5GC may comprise one or more AMF/User PlanFunction (UPF) functions (e.g. 130A or 130B). A gNB or an ng-eNB may beconnected to a UPF by means of an NG-User plane (NG-U) interface. TheNG-U interface may provide delivery (e.g. non-guaranteed delivery) ofuser plane Protocol Data Units (PDUs) between a RAN node and the UPF. AgNB or an ng-eNB may be connected to an AMF by means of an NG-Controlplane (NG-C) interface. The NG-C interface may provide, for example, NGinterface management, UE context management, UE mobility management,transport of NAS messages, paging, PDU session management, configurationtransfer and/or warning message transmission, combinations thereof,and/or the like.

In an example, a UPF may host functions such as anchor point forintra-/inter-Radio Access Technology (RAT) mobility (when applicable),external PDU session point of interconnect to data network, packetrouting and forwarding, packet inspection and user plane part of policyrule enforcement, traffic usage reporting, uplink classifier to supportrouting traffic flows to a data network, branching point to supportmulti-homed PDU session, QoS handling for user plane, e.g. packetfiltering, gating, Uplink (UL)/Downlink (DL) rate enforcement, uplinktraffic verification (e.g. Service Data Flow (SDF) to QoS flow mapping),downlink packet buffering and/or downlink data notification triggering.

In an example, an AMF may host functions such as NAS signalingtermination, NAS signaling security, Access Stratum (AS) securitycontrol, inter Core Network (CN) node signaling for mobility between3^(rd) Generation Partnership Project (3GPP) access networks, idle modeUE reachability (e.g., control and execution of paging retransmission),registration area management, support of intra-system and inter-systemmobility, access authentication, access authorization including check ofroaming rights, mobility management control (subscription and policies),support of network slicing and/or Session Management Function (SMF)selection.

FIG. 2A is an example user plane protocol stack, where Service DataAdaptation Protocol (SDAP) (e.g. 211 and 221), Packet Data ConvergenceProtocol (PDCP) (e.g. 212 and 222), Radio Link Control (RLC) (e.g. 213and 223) and Media Access Control (MAC) (e.g. 214 and 224) sublayers andPhysical (PHY) (e.g. 215 and 225) layer may be terminated in wirelessdevice (e.g. 110) and gNB (e.g. 120) on the network side. In an example,a PHY layer provides transport services to higher layers (e.g. MAC, RRC,etc.). In an example, services and functions of a MAC sublayer maycomprise mapping between logical channels and transport channels,multiplexing/demultiplexing of MAC Service Data Units (SDUs) belongingto one or different logical channels into/from Transport Blocks (TBs)delivered to/from the PHY layer, scheduling information reporting, errorcorrection through Hybrid Automatic Repeat request (HARQ) (e.g. one HARQentity per carrier in case of Carrier Aggregation (CA)), priorityhandling between UEs by means of dynamic scheduling, priority handlingbetween logical channels of one UE by means of logical channelprioritization, and/or padding. A MAC entity may support one or multiplenumerologies and/or transmission timings. In an example, mappingrestrictions in a logical channel prioritization may control whichnumerology and/or transmission timing a logical channel may use. In anexample, an RLC sublayer may supports transparent mode (TM),unacknowledged mode (UM) and acknowledged mode (AM) transmission modes.The RLC configuration may be per logical channel with no dependency onnumerologies and/or Transmission Time Interval (TTI) durations. In anexample, Automatic Repeat Request (ARQ) may operate on any of thenumerologies and/or TTI durations the logical channel is configuredwith. In an example, services and functions of the PDCP layer for theuser plane may comprise sequence numbering, header compression anddecompression, transfer of user data, reordering and duplicatedetection, PDCP PDU routing (e.g. in case of split bearers),retransmission of PDCP SDUs, ciphering, deciphering and integrityprotection, PDCP SDU discard, PDCP re-establishment and data recoveryfor RLC AM, and/or duplication of PDCP PDUs. In an example, services andfunctions of SDAP may comprise mapping between a QoS flow and a dataradio bearer. In an example, services and functions of SDAP may comprisemapping Quality of Service Indicator (QFI) in DL and UL packets. In anexample, a protocol entity of SDAP may be configured for an individualPDU session.

FIG. 2B is an example control plane protocol stack where PDCP (e.g. 233and 242), RLC (e.g. 234 and 243) and MAC (e.g. 235 and 244) sublayersand PHY (e.g. 236 and 245) layer may be terminated in wireless device(e.g. 110) and gNB (e.g. 120) on a network side and perform service andfunctions described above. In an example, RRC (e.g. 232 and 241) may beterminated in a wireless device and a gNB on a network side. In anexample, services and functions of RRC may comprise broadcast of systeminformation related to AS and NAS, paging initiated by 5GC or RAN,establishment, maintenance and release of an RRC connection between theUE and RAN, security functions including key management, establishment,configuration, maintenance and release of Signaling Radio Bearers (SRBs)and Data Radio Bearers (DRBs), mobility functions, QoS managementfunctions, UE measurement reporting and control of the reporting,detection of and recovery from radio link failure, and/or NAS messagetransfer to/from NAS from/to a UE. In an example, NAS control protocol(e.g. 231 and 251) may be terminated in the wireless device and AMF(e.g. 130) on a network side and may perform functions such asauthentication, mobility management between a UE and a AMF for 3GPPaccess and non-3GPP access, and session management between a UE and aSMF for 3GPP access and non-3GPP access.

In an example, a base station may configure a plurality of logicalchannels for a wireless device. A logical channel in the plurality oflogical channels may correspond to a radio bearer and the radio bearermay be associated with a QoS requirement. In an example, a base stationmay configure a logical channel to be mapped to one or moreTTIs/numerologies in a plurality of TTIs/numerologies. The wirelessdevice may receive a Downlink Control Information (DCI) via PhysicalDownlink Control CHannel (PDCCH) indicating an uplink grant. In anexample, the uplink grant may be for a first TTI/numerology and mayindicate uplink resources for transmission of a transport block. Thebase station may configure each logical channel in the plurality oflogical channels with one or more parameters to be used by a logicalchannel prioritization procedure at the MAC layer of the wirelessdevice. The one or more parameters may comprise priority, prioritizedbit rate, etc. A logical channel in the plurality of logical channelsmay correspond to one or more buffers comprising data associated withthe logical channel. The logical channel prioritization procedure mayallocate the uplink resources to one or more first logical channels inthe plurality of logical channels and/or one or more MAC ControlElements (CEs). The one or more first logical channels may be mapped tothe first TTI/numerology. The MAC layer at the wireless device maymultiplex one or more MAC CEs and/or one or more MAC SDUs (e.g., logicalchannel) in a MAC PDU (e.g., transport block). In an example, the MACPDU may comprise a MAC header comprising a plurality of MAC sub-headers.A MAC sub-header in the plurality of MAC sub-headers may correspond to aMAC CE or a MAC SUD (logical channel) in the one or more MAC CEs and/orone or more MAC SDUs. In an example, a MAC CE or a logical channel maybe configured with a Logical Channel IDentifier (LCID). In an example,LCID for a logical channel or a MAC CE may be fixed/pre-configured. Inan example, LCID for a logical channel or MAC CE may be configured forthe wireless device by the base station. The MAC sub-headercorresponding to a MAC CE or a MAC SDU may comprise LCID associated withthe MAC CE or the MAC SDU.

In an example, a base station may activate and/or deactivate and/orimpact one or more processes (e.g., set values of one or more parametersof the one or more processes or start and/or stop one or more timers ofthe one or more processes) at the wireless device by employing one ormore MAC commands. The one or more MAC commands may comprise one or moreMAC control elements. In an example, the one or more processes maycomprise activation and/or deactivation of PDCP packet duplication forone or more radio bearers. The base station may transmit a MAC CEcomprising one or more fields, the values of the fields indicatingactivation and/or deactivation of PDCP duplication for the one or moreradio bearers. In an example, the one or more processes may compriseChannel State Information (CSI) transmission of on one or more cells.The base station may transmit one or more MAC CEs indicating activationand/or deactivation of the CSI transmission on the one or more cells. Inan example, the one or more processes may comprise activation ordeactivation of one or more secondary cells. In an example, the basestation may transmit a MA CE indicating activation or deactivation ofone or more secondary cells. In an example, the base station maytransmit one or more MAC CEs indicating starting and/or stopping one ormore Discontinuous Reception (DRX) timers at the wireless device. In anexample, the base station may transmit one or more MAC CEs indicatingone or more timing advance values for one or more Timing Advance Groups(TAGs).

FIG. 3 is a block diagram of base stations (base station 1, 120A, andbase station 2, 120B) and a wireless device 110. A wireless device maybe called an UE. A base station may be called a NB, eNB, gNB, and/orng-eNB. In an example, a wireless device and/or a base station may actas a relay node. The base station 1, 120A, may comprise at least onecommunication interface 320A (e.g. a wireless modem, an antenna, a wiredmodem, and/or the like), at least one processor 321A, and at least oneset of program code instructions 323A stored in non-transitory memory322A and executable by the at least one processor 321A. The base station2, 120B, may comprise at least one communication interface 320B, atleast one processor 321B, and at least one set of program codeinstructions 323B stored in non-transitory memory 322B and executable bythe at least one processor 321B.

A base station may comprise many sectors for example: 1, 2, 3, 4, or 6sectors. A base station may comprise many cells, for example, rangingfrom 1 to 50 cells or more. A cell may be categorized, for example, as aprimary cell or secondary cell. At Radio Resource Control (RRC)connection establishment/re-establishment/handover, one serving cell mayprovide the NAS (non-access stratum) mobility information (e.g. TrackingArea Identifier (TAI)). At RRC connection re-establishment/handover, oneserving cell may provide the security input. This cell may be referredto as the Primary Cell (PCell). In the downlink, a carrier correspondingto the PCell may be a DL Primary Component Carrier (PCC), while in theuplink, a carrier may be an UL PCC. Depending on wireless devicecapabilities, Secondary Cells (SCells) may be configured to formtogether with a PCell a set of serving cells. In a downlink, a carriercorresponding to an SCell may be a downlink secondary component carrier(DL SCC), while in an uplink, a carrier may be an uplink secondarycomponent carrier (UL SCC). An SCell may or may not have an uplinkcarrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned a physical cell ID and a cell index. A carrier (downlinkor uplink) may belong to one cell. The cell ID or cell index may alsoidentify the downlink carrier or uplink carrier of the cell (dependingon the context it is used). In the disclosure, a cell ID may be equallyreferred to a carrier ID, and a cell index may be referred to a carrierindex. In an implementation, a physical cell ID or a cell index may beassigned to a cell. A cell ID may be determined using a synchronizationsignal transmitted on a downlink carrier. A cell index may be determinedusing RRC messages. For example, when the disclosure refers to a firstphysical cell ID for a first downlink carrier, the disclosure may meanthe first physical cell ID is for a cell comprising the first downlinkcarrier. The same concept may apply to, for example, carrier activation.When the disclosure indicates that a first carrier is activated, thespecification may equally mean that a cell comprising the first carrieris activated.

A base station may transmit to a wireless device one or more messages(e.g. RRC messages) comprising a plurality of configuration parametersfor one or more cells. One or more cells may comprise at least oneprimary cell and at least one secondary cell. In an example, an RRCmessage may be broadcasted or unicasted to the wireless device. In anexample, configuration parameters may comprise common parameters anddedicated parameters.

Services and/or functions of an RRC sublayer may comprise at least oneof: broadcast of system information related to AS and NAS; paginginitiated by 5GC and/or NG-RAN; establishment, maintenance, and/orrelease of an RRC connection between a wireless device and NG-RAN, whichmay comprise at least one of addition, modification and release ofcarrier aggregation; or addition, modification, and/or release of dualconnectivity in NR or between E-UTRA and NR. Services and/or functionsof an RRC sublayer may further comprise at least one of securityfunctions comprising key management; establishment, configuration,maintenance, and/or release of Signaling Radio Bearers (SRBs) and/orData Radio Bearers (DRBs); mobility functions which may comprise atleast one of a handover (e.g. intra NR mobility or inter-RAT mobility)and a context transfer; or a wireless device cell selection andreselection and control of cell selection and reselection. Servicesand/or functions of an RRC sublayer may further comprise at least one ofQoS management functions; a wireless device measurementconfiguration/reporting; detection of and/or recovery from radio linkfailure; or NAS message transfer to/from a core network entity (e.g.AMF, Mobility Management Entity (MME)) from/to the wireless device.

An RRC sublayer may support an RRC_Idle state, an RRC_Inactive stateand/or an RRC_Connected state for a wireless device. In an RRC_Idlestate, a wireless device may perform at least one of: Public Land MobileNetwork (PLMN) selection; receiving broadcasted system information; cellselection/re-selection; monitoring/receiving a paging for mobileterminated data initiated by 5GC; paging for mobile terminated data areamanaged by 5GC; or DRX for CN paging configured via NAS. In anRRC_Inactive state, a wireless device may perform at least one of:receiving broadcasted system information; cell selection/re-selection;monitoring/receiving a RAN/CN paging initiated by NG-RAN/5GC; RAN-basednotification area (RNA) managed by NG-RAN; or DRX for RAN/CN pagingconfigured by NG-RAN/NAS. In an RRC_Idle state of a wireless device, abase station (e.g. NG-RAN) may keep a 5GC-NG-RAN connection (bothC/U-planes) for the wireless device; and/or store a UE AS context forthe wireless device. In an RRC_Connected state of a wireless device, abase station (e.g. NG-RAN) may perform at least one of: establishment of5GC-NG-RAN connection (both C/U-planes) for the wireless device; storinga UE AS context for the wireless device; transmit/receive of unicastdata to/from the wireless device; or network-controlled mobility basedon measurement results received from the wireless device. In anRRC_Connected state of a wireless device, an NG-RAN may know a cell thatthe wireless device belongs to.

System information (SI) may be divided into minimum SI and other SI. Theminimum SI may be periodically broadcast. The minimum SI may comprisebasic information required for initial access and information foracquiring any other SI broadcast periodically or provisioned on-demand,i.e. scheduling information. The other SI may either be broadcast, or beprovisioned in a dedicated manner, either triggered by a network or uponrequest from a wireless device. A minimum SI may be transmitted via twodifferent downlink channels using different messages (e.g.MasterInformationBlock and SystemInformationBlockType1). Another SI maybe transmitted via SystemInformationBlockType2. For a wireless device inan RRC_Connected state, dedicated RRC signaling may be employed for therequest and delivery of the other SI. For the wireless device in theRRC_Idle state and/or the RRC_Inactive state, the request may trigger arandom-access procedure.

A wireless device may report its radio access capability informationwhich may be static. A base station may request what capabilities for awireless device to report based on band information. When allowed by anetwork, a temporary capability restriction request may be sent by thewireless device to signal the limited availability of some capabilities(e.g. due to hardware sharing, interference or overheating) to the basestation. The base station may confirm or reject the request. Thetemporary capability restriction may be transparent to 5GC (e.g., staticcapabilities may be stored in 5GC).

When CA is configured, a wireless device may have an RRC connection witha network. At RRC connection establishment/re-establishment/handoverprocedure, one serving cell may provide NAS mobility information, and atRRC connection re-establishment/handover, one serving cell may provide asecurity input. This cell may be referred to as the PCell. Depending onthe capabilities of the wireless device, SCells may be configured toform together with the PCell a set of serving cells. The configured setof serving cells for the wireless device may comprise one PCell and oneor more SCells.

The reconfiguration, addition and removal of SCells may be performed byRRC. At intra-NR handover, RRC may also add, remove, or reconfigureSCells for usage with the target PCell. When adding a new SCell,dedicated RRC signaling may be employed to send all required systeminformation of the SCell i.e. while in connected mode, wireless devicesmay not need to acquire broadcasted system information directly from theSCells.

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells and cell groups). As part of the RRCconnection reconfiguration procedure, NAS dedicated information may betransferred from the network to the wireless device. TheRRCConnectionReconfiguration message may be a command to modify an RRCconnection. It may convey information for measurement configuration,mobility control, radio resource configuration (e.g. RBs, MAC mainconfiguration and physical channel configuration) comprising anyassociated dedicated NAS information and security configuration. If thereceived RRC Connection Reconfiguration message comprises thesCellToReleaseList, the wireless device may perform an SCell release. Ifthe received RRC Connection Reconfiguration message comprises thesCellToAddModList, the wireless device may perform SCell additions ormodification.

An RRC connection establishment (or reestablishment, resume) proceduremay be to establish (or reestablish, resume) an RRC connection. an RRCconnection establishment procedure may comprise SRB1 establishment. TheRRC connection establishment procedure may be used to transfer theinitial NAS dedicated information/message from a wireless device toE-UTRAN. The RRCConnectionReestablishment message may be used tore-establish SRB1.

A measurement report procedure may be to transfer measurement resultsfrom a wireless device to NG-RAN. The wireless device may initiate ameasurement report procedure after successful security activation. Ameasurement report message may be employed to transmit measurementresults.

The wireless device 110 may comprise at least one communicationinterface 310 (e.g. a wireless modem, an antenna, and/or the like), atleast one processor 314, and at least one set of program codeinstructions 316 stored in non-transitory memory 315 and executable bythe at least one processor 314. The wireless device 110 may furthercomprise at least one of at least one speaker/microphone 311, at leastone keypad 312, at least one display/touchpad 313, at least one powersource 317, at least one global positioning system (GPS) chipset 318,and other peripherals 319.

The processor 314 of the wireless device 110, the processor 321A of thebase station 1 120A, and/or the processor 321B of the base station 2120B may comprise at least one of a general-purpose processor, a digitalsignal processor (DSP), a controller, a microcontroller, an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) and/or other programmable logic device, discrete gate and/ortransistor logic, discrete hardware components, and the like. Theprocessor 314 of the wireless device 110, the processor 321A in basestation 1 120A, and/or the processor 321B in base station 2 120B mayperform at least one of signal coding/processing, data processing, powercontrol, input/output processing, and/or any other functionality thatmay enable the wireless device 110, the base station 1 120A and/or thebase station 2 120B to operate in a wireless environment.

The processor 314 of the wireless device 110 may be connected to thespeaker/microphone 311, the keypad 312, and/or the display/touchpad 313.The processor 314 may receive user input data from and/or provide useroutput data to the speaker/microphone 311, the keypad 312, and/or thedisplay/touchpad 313. The processor 314 in the wireless device 110 mayreceive power from the power source 317 and/or may be configured todistribute the power to the other components in the wireless device 110.The power source 317 may comprise at least one of one or more dry cellbatteries, solar cells, fuel cells, and the like. The processor 314 maybe connected to the GPS chipset 318. The GPS chipset 318 may beconfigured to provide geographic location information of the wirelessdevice 110.

The processor 314 of the wireless device 110 may further be connected toother peripherals 319, which may comprise one or more software and/orhardware modules that provide additional features and/orfunctionalities. For example, the peripherals 319 may comprise at leastone of an accelerometer, a satellite transceiver, a digital camera, auniversal serial bus (USB) port, a hands-free headset, a frequencymodulated (FM) radio unit, a media player, an Internet browser, and thelike.

The communication interface 320A of the base station 1, 120A, and/or thecommunication interface 320B of the base station 2, 120B, may beconfigured to communicate with the communication interface 310 of thewireless device 110 via a wireless link 330A and/or a wireless link 330Brespectively. In an example, the communication interface 320A of thebase station 1, 120A, may communicate with the communication interface320B of the base station 2 and other RAN and core network nodes.

The wireless link 330A and/or the wireless link 330B may comprise atleast one of a bi-directional link and/or a directional link. Thecommunication interface 310 of the wireless device 110 may be configuredto communicate with the communication interface 320A of the base station1 120A and/or with the communication interface 320B of the base station2 120B. The base station 1 120A and the wireless device 110 and/or thebase station 2 120B and the wireless device 110 may be configured tosend and receive transport blocks via the wireless link 330A and/or viathe wireless link 330B, respectively. The wireless link 330A and/or thewireless link 330B may employ at least one frequency carrier. Accordingto some of various aspects of embodiments, transceiver(s) may beemployed. A transceiver may be a device that comprises both atransmitter and a receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in thecommunication interface 310, 320A, 320B and the wireless link 330A, 330Bare illustrated in FIG. 4A, FIG. 4B, FIG. 4C, FIG. 4D, FIG. 6, FIG. 7A,FIG. 7B, FIG. 8, and associated text.

In an example, other nodes in a wireless network (e.g. AMF, UPF, SMF,etc.) may comprise one or more communication interfaces, one or moreprocessors, and memory storing instructions.

A node (e.g. wireless device, base station, AMF, SMF, UPF, servers,switches, antennas, and/or the like) may comprise one or moreprocessors, and memory storing instructions that when executed by theone or more processors causes the node to perform certain processesand/or functions. Example embodiments may enable operation ofsingle-carrier and/or multi-carrier communications. Other exampleembodiments may comprise a non-transitory tangible computer readablemedia comprising instructions executable by one or more processors tocause operation of single-carrier and/or multi-carrier communications.Yet other example embodiments may comprise an article of manufacturethat comprises a non-transitory tangible computer readablemachine-accessible medium having instructions encoded thereon forenabling programmable hardware to cause a node to enable operation ofsingle-carrier and/or multi-carrier communications. The node maycomprise processors, memory, interfaces, and/or the like.

An interface may comprise at least one of a hardware interface, afirmware interface, a software interface, and/or a combination thereof.The hardware interface may comprise connectors, wires, electronicdevices such as drivers, amplifiers, and/or the like. The softwareinterface may comprise code stored in a memory device to implementprotocol(s), protocol layers, communication drivers, device drivers,combinations thereof, and/or the like. The firmware interface maycomprise a combination of embedded hardware and code stored in and/or incommunication with a memory device to implement connections, electronicdevice operations, protocol(s), protocol layers, communication drivers,device drivers, hardware operations, combinations thereof, and/or thelike.

FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure. FIG. 4A shows an example uplink transmitter forat least one physical channel A baseband signal representing a physicaluplink shared channel may perform one or more functions. The one or morefunctions may comprise at least one of: scrambling; modulation ofscrambled bits to generate complex-valued symbols; mapping of thecomplex-valued modulation symbols onto one or several transmissionlayers; transform precoding to generate complex-valued symbols;precoding of the complex-valued symbols; mapping of precodedcomplex-valued symbols to resource elements; generation ofcomplex-valued time-domain Single Carrier-Frequency Division MultipleAccess (SC-FDMA) or CP-OFDM signal for an antenna port; and/or the like.In an example, when transform precoding is enabled, a SC-FDMA signal foruplink transmission may be generated. In an example, when transformprecoding is not enabled, an CP-OFDM signal for uplink transmission maybe generated by FIG. 4A. These functions are illustrated as examples andit is anticipated that other mechanisms may be implemented in variousembodiments.

An example structure for modulation and up-conversion to the carrierfrequency of the complex-valued SC-FDMA or CP-OFDM baseband signal foran antenna port and/or the complex-valued Physical Random Access CHannel(PRACH) baseband signal is shown in FIG. 4B. Filtering may be employedprior to transmission.

An example structure for downlink transmissions is shown in FIG. 4C. Thebaseband signal representing a downlink physical channel may perform oneor more functions. The one or more functions may comprise: scrambling ofcoded bits in a codeword to be transmitted on a physical channel;modulation of scrambled bits to generate complex-valued modulationsymbols; mapping of the complex-valued modulation symbols onto one orseveral transmission layers; precoding of the complex-valued modulationsymbols on a layer for transmission on the antenna ports; mapping ofcomplex-valued modulation symbols for an antenna port to resourceelements; generation of complex-valued time-domain OFDM signal for anantenna port; and/or the like. These functions are illustrated asexamples and it is anticipated that other mechanisms may be implementedin various embodiments.

In an example, a base station may transmit a first symbol and a secondsymbol on an antenna port, to a wireless device. The wireless device mayinfer the channel (e.g., fading gain, multipath delay, etc.) forconveying the second symbol on the antenna port, from the channel forconveying the first symbol on the antenna port. In an example, a firstantenna port and a second antenna port may be quasi co-located if one ormore large-scale properties of the channel over which a first symbol onthe first antenna port is conveyed may be inferred from the channel overwhich a second symbol on a second antenna port is conveyed. The one ormore large-scale properties may comprise at least one of: delay spread;doppler spread; doppler shift; average gain; average delay; and/orspatial Receiving (Rx) parameters.

An example modulation and up-conversion to the carrier frequency of thecomplex-valued OFDM baseband signal for an antenna port is shown in FIG.4D. Filtering may be employed prior to transmission.

FIG. 5A is a diagram of an example uplink channel mapping and exampleuplink physical signals. FIG. 5B is a diagram of an example downlinkchannel mapping and a downlink physical signals. In an example, aphysical layer may provide one or more information transfer services toa MAC and/or one or more higher layers. For example, the physical layermay provide the one or more information transfer services to the MAC viaone or more transport channels. An information transfer service mayindicate how and with what characteristics data are transferred over theradio interface.

In an example embodiment, a radio network may comprise one or moredownlink and/or uplink transport channels. For example, a diagram inFIG. 5A shows example uplink transport channels comprising Uplink-SharedCHannel (UL-SCH) 501 and Random Access CHannel (RACH) 502. A diagram inFIG. 5B shows example downlink transport channels comprisingDownlink-Shared CHannel (DL-SCH) 511, Paging CHannel (PCH) 512, andBroadcast CHannel (BCH) 513. A transport channel may be mapped to one ormore corresponding physical channels. For example, UL-SCH 501 may bemapped to Physical Uplink Shared CHannel (PUSCH) 503. RACH 502 may bemapped to PRACH 505. DL-SCH 511 and PCH 512 may be mapped to PhysicalDownlink Shared CHannel (PDSCH) 514. BCH 513 may be mapped to PhysicalBroadcast CHannel (PBCH) 516.

There may be one or more physical channels without a correspondingtransport channel. The one or more physical channels may be employed forUplink Control Information (UCI) 509 and/or Downlink Control Information(DCI) 517. For example, Physical Uplink Control CHannel (PUCCH) 504 maycarry UCI 509 from a UE to a base station. For example, PhysicalDownlink Control CHannel (PDCCH) 515 may carry DCI 517 from a basestation to a UE. NR may support UCI 509 multiplexing in PUSCH 503 whenUCI 509 and PUSCH 503 transmissions may coincide in a slot at least inpart. The UCI 509 may comprise at least one of CSI, Acknowledgement(ACK)/Negative Acknowledgement (NACK), and/or scheduling request. TheDCI 517 on PDCCH 515 may indicate at least one of following: one or moredownlink assignments and/or one or more uplink scheduling grants

In uplink, a UE may transmit one or more Reference Signals (RSs) to abase station. For example, the one or more RSs may be at least one ofDemodulation-RS (DM-RS) 506, Phase Tracking-RS (PT-RS) 507, and/orSounding RS (SRS) 508. In downlink, a base station may transmit (e.g.,unicast, multicast, and/or broadcast) one or more RSs to a UE. Forexample, the one or more RSs may be at least one of PrimarySynchronization Signal (PSS)/Secondary Synchronization Signal (SSS) 521,CSI-RS 522, DM-RS 523, and/or PT-RS 524.

In an example, a UE may transmit one or more uplink DM-RSs 506 to a basestation for channel estimation, for example, for coherent demodulationof one or more uplink physical channels (e.g., PUSCH 503 and/or PUCCH504). For example, a UE may transmit a base station at least one uplinkDM-RS 506 with PUSCH 503 and/or PUCCH 504, wherein the at least oneuplink DM-RS 506 may be spanning a same frequency range as acorresponding physical channel. In an example, a base station mayconfigure a UE with one or more uplink DM-RS configurations. At leastone DM-RS configuration may support a front-loaded DM-RS pattern. Afront-loaded DM-RS may be mapped over one or more OFDM symbols (e.g., 1or 2 adjacent OFDM symbols). One or more additional uplink DM-RS may beconfigured to transmit at one or more symbols of a PUSCH and/or PUCCH. Abase station may semi-statically configure a UE with a maximum number offront-loaded DM-RS symbols for PUSCH and/or PUCCH. For example, a UE mayschedule a single-symbol DM-RS and/or double symbol DM-RS based on amaximum number of front-loaded DM-RS symbols, wherein a base station mayconfigure the UE with one or more additional uplink DM-RS for PUSCHand/or PUCCH. A new radio network may support, e.g., at least forCP-OFDM, a common DM-RS structure for DL and UL, wherein a DM-RSlocation, DM-RS pattern, and/or scrambling sequence may be same ordifferent.

In an example, whether uplink PT-RS 507 is present or not may depend ona RRC configuration. For example, a presence of uplink PT-RS may beUE-specifically configured. For example, a presence and/or a pattern ofuplink PT-RS 507 in a scheduled resource may be UE-specificallyconfigured by a combination of RRC signaling and/or association with oneor more parameters employed for other purposes (e.g., Modulation andCoding Scheme (MCS)) which may be indicated by DCI. When configured, adynamic presence of uplink PT-RS 507 may be associated with one or moreDCI parameters comprising at least MCS. A radio network may supportplurality of uplink PT-RS densities defined in time/frequency domain.When present, a frequency domain density may be associated with at leastone configuration of a scheduled bandwidth. A UE may assume a sameprecoding for a DMRS port and a PT-RS port. A number of PT-RS ports maybe fewer than a number of DM-RS ports in a scheduled resource. Forexample, uplink PT-RS 507 may be confined in the scheduledtime/frequency duration for a UE.

In an example, a UE may transmit SRS 508 to a base station for channelstate estimation to support uplink channel dependent scheduling and/orlink adaptation. For example, SRS 508 transmitted by a UE may allow fora base station to estimate an uplink channel state at one or moredifferent frequencies. A base station scheduler may employ an uplinkchannel state to assign one or more resource blocks of good quality foran uplink PUSCH transmission from a UE. A base station maysemi-statically configure a UE with one or more SRS resource sets. Foran SRS resource set, a base station may configure a UE with one or moreSRS resources. An SRS resource set applicability may be configured by ahigher layer (e.g., RRC) parameter. For example, when a higher layerparameter indicates beam management, a SRS resource in each of one ormore SRS resource sets may be transmitted at a time instant. A UE maytransmit one or more SRS resources in different SRS resource setssimultaneously. A new radio network may support aperiodic, periodicand/or semi-persistent SRS transmissions. A UE may transmit SRSresources based on one or more trigger types, wherein the one or moretrigger types may comprise higher layer signaling (e.g., RRC) and/or oneor more DCI formats (e.g., at least one DCI format may be employed for aUE to select at least one of one or more configured SRS resource sets.An SRS trigger type 0 may refer to an SRS triggered based on a higherlayer signaling. An SRS trigger type 1 may refer to an SRS triggeredbased on one or more DCI formats. In an example, when PUSCH 503 and SRS508 are transmitted in a same slot, a UE may be configured to transmitSRS 508 after a transmission of PUSCH 503 and corresponding uplink DM-RS506.

In an example, a base station may semi-statically configure a UE withone or more SRS configuration parameters indicating at least one offollowing: a SRS resource configuration identifier, a number of SRSports, time domain behavior of SRS resource configuration (e.g., anindication of periodic, semi-persistent, or aperiodic SRS), slot(mini-slot, and/or subframe) level periodicity and/or offset for aperiodic and/or aperiodic SRS resource, a number of OFDM symbols in aSRS resource, starting OFDM symbol of a SRS resource, a SRS bandwidth, afrequency hopping bandwidth, a cyclic shift, and/or a SRS sequence ID.

In an example, in a time domain, an SS/PBCH block may comprise one ormore OFDM symbols (e.g., 4 OFDM symbols numbered in increasing orderfrom 0 to 3) within the SS/PBCH block. An SS/PBCH block may comprisePSS/SSS 521 and PBCH 516. In an example, in the frequency domain, anSS/PBCH block may comprise one or more contiguous subcarriers (e.g., 240contiguous subcarriers with the subcarriers numbered in increasing orderfrom 0 to 239) within the SS/PBCH block. For example, a PSS/SSS 521 mayoccupy 1 OFDM symbol and 127 subcarriers. For example, PBCH 516 may spanacross 3 OFDM symbols and 240 subcarriers. A UE may assume that one ormore SS/PBCH blocks transmitted with a same block index may be quasico-located, e.g., with respect to Doppler spread, Doppler shift, averagegain, average delay, and spatial Rx parameters. A UE may not assumequasi co-location for other SS/PBCH block transmissions. A periodicityof an SS/PBCH block may be configured by a radio network (e.g., by anRRC signaling) and one or more time locations where the SS/PBCH blockmay be sent may be determined by sub-carrier spacing. In an example, aUE may assume a band-specific sub-carrier spacing for an SS/PBCH blockunless a radio network has configured a UE to assume a differentsub-carrier spacing.

In an example, downlink CSI-RS 522 may be employed for a UE to acquirechannel state information. A radio network may support periodic,aperiodic, and/or semi-persistent transmission of downlink CSI-RS 522.For example, a base station may semi-statically configure and/orreconfigure a UE with periodic transmission of downlink CSI-RS 522. Aconfigured CSI-RS resources may be activated ad/or deactivated. Forsemi-persistent transmission, an activation and/or deactivation ofCSI-RS resource may be triggered dynamically. In an example, CSI-RSconfiguration may comprise one or more parameters indicating at least anumber of antenna ports. For example, a base station may configure a UEwith 32 ports. A base station may semi-statically configure a UE withone or more CSI-RS resource sets. One or more CSI-RS resources may beallocated from one or more CSI-RS resource sets to one or more UEs. Forexample, a base station may semi-statically configure one or moreparameters indicating CSI RS resource mapping, for example, time-domainlocation of one or more CSI-RS resources, a bandwidth of a CSI-RSresource, and/or a periodicity. In an example, a UE may be configured toemploy a same OFDM symbols for downlink CSI-RS 522 and control resourceset (coreset) when the downlink CSI-RS 522 and coreset are spatiallyquasi co-located and resource elements associated with the downlinkCSI-RS 522 are the outside of PRBs configured for coreset. In anexample, a UE may be configured to employ a same OFDM symbols fordownlink CSI-RS 522 and SSB/PBCH when the downlink CSI-RS 522 andSSB/PBCH are spatially quasi co-located and resource elements associatedwith the downlink CSI-RS 522 are the outside of PRBs configured forSSB/PBCH.

In an example, a UE may transmit one or more downlink DM-RSs 523 to abase station for channel estimation, for example, for coherentdemodulation of one or more downlink physical channels (e.g., PDSCH514). For example, a radio network may support one or more variableand/or configurable DM-RS patterns for data demodulation. At least onedownlink DM-RS configuration may support a front-loaded DM-RS pattern. Afront-loaded DM-RS may be mapped over one or more OFDM symbols (e.g., 1or 2 adjacent OFDM symbols). A base station may semi-staticallyconfigure a UE with a maximum number of front-loaded DM-RS symbols forPDSCH 514. For example, a DM-RS configuration may support one or moreDM-RS ports. For example, for single user-MIMO, a DM-RS configurationmay support at least 8 orthogonal downlink DM-RS ports. For example, formultiuser-MIMO, a DM-RS configuration may support 12 orthogonal downlinkDM-RS ports. A radio network may support, e.g., at least for CP-OFDM, acommon DM-RS structure for DL and UL, wherein a DM-RS location, DM-RSpattern, and/or scrambling sequence may be same or different.

In an example, whether downlink PT-RS 524 is present or not may dependon a RRC configuration. For example, a presence of downlink PT-RS 524may be UE-specifically configured. For example, a presence and/or apattern of downlink PT-RS 524 in a scheduled resource may beUE-specifically configured by a combination of RRC signaling and/orassociation with one or more parameters employed for other purposes(e.g., MCS) which may be indicated by DCI. When configured, a dynamicpresence of downlink PT-RS 524 may be associated with one or more DCIparameters comprising at least MCS. A radio network may supportplurality of PT-RS densities defined in time/frequency domain. Whenpresent, a frequency domain density may be associated with at least oneconfiguration of a scheduled bandwidth. A UE may assume a same precodingfor a DMRS port and a PT-RS port. A number of PT-RS ports may be fewerthan a number of DM-RS ports in a scheduled resource. For example,downlink PT-RS 524 may be confined in the scheduled time/frequencyduration for a UE.

FIG. 6 is a diagram depicting an example frame structure for a carrieras per an aspect of an embodiment of the present disclosure. Amulticarrier OFDM communication system may comprise one or morecarriers, for example, ranging from 1 to 32 carriers, in case of carrieraggregation, or ranging from 1 to 64 carriers, in case of dualconnectivity. Different radio frame structures may be supported (e.g.,for FDD and for TDD duplex mechanisms). FIG. 6 shows an example framestructure. Downlink and uplink transmissions may be organized into radioframes 601. In this example, radio frame duration is 10 ms. In thisexample, a 10 ms radio frame 601 may be divided into ten equally sizedsubframes 602 with 1 ms duration. Subframe(s) may comprise one or moreslots (e.g. slots 603 and 605) depending on subcarrier spacing and/or CPlength. For example, a subframe with 15 kHz, 30 kHz, 60 kHz, 120 kHz,240 kHz and 480 kHz subcarrier spacing may comprise one, two, four,eight, sixteen and thirty-two slots, respectively. In FIG. 6, a subframemay be divided into two equally sized slots 603 with 0.5 ms duration.For example, 10 subframes may be available for downlink transmission and10 subframes may be available for uplink transmissions in a 10 msinterval. Uplink and downlink transmissions may be separated in thefrequency domain. Slot(s) may comprise a plurality of OFDM symbols 604.The number of OFDM symbols 604 in a slot 605 may depend on the cyclicprefix length. For example, a slot may be 14 OFDM symbols for the samesubcarrier spacing of up to 480 kHz with normal CP. A slot may be 12OFDM symbols for the same subcarrier spacing of 60 kHz with extended CP.A slot may contain downlink, uplink, or a downlink part and an uplinkpart and/or alike.

FIG. 7A is a diagram depicting example sets of OFDM subcarriers as peran aspect of an embodiment of the present disclosure. In the example, agNB may communicate with a wireless device with a carrier with anexample channel bandwidth 700. Arrow(s) in the diagram may depict asubcarrier in a multicarrier OFDM system. The OFDM system may usetechnology such as OFDM technology, SC-FDMA technology, and/or the like.In an example, an arrow 701 shows a subcarrier transmitting informationsymbols. In an example, a subcarrier spacing 702, between two contiguoussubcarriers in a carrier, may be any one of 15 KHz, 30 KHz, 60 KHz, 120KHz, 240 KHz etc. In an example, different subcarrier spacing maycorrespond to different transmission numerologies. In an example, atransmission numerology may comprise at least: a numerology index; avalue of subcarrier spacing; a type of cyclic prefix (CP). In anexample, a gNB may transmit to/receive from a UE on a number ofsubcarriers 703 in a carrier. In an example, a bandwidth occupied by anumber of subcarriers 703 (transmission bandwidth) may be smaller thanthe channel bandwidth 700 of a carrier, due to guard band 704 and 705.In an example, a guard band 704 and 705 may be used to reduceinterference to and from one or more neighbor carriers. A number ofsubcarriers (transmission bandwidth) in a carrier may depend on thechannel bandwidth of the carrier and the subcarrier spacing. Forexample, a transmission bandwidth, for a carrier with 20 MHz channelbandwidth and 15 KHz subcarrier spacing, may be in number of 1024subcarriers.

In an example, a gNB and a wireless device may communicate with multipleCCs when configured with CA. In an example, different component carriersmay have different bandwidth and/or subcarrier spacing, if CA issupported. In an example, a gNB may transmit a first type of service toa UE on a first component carrier. The base station may transmit asecond type of service to the UE on a second component carrier.Different type of services may have different service requirement (e.g.,data rate, latency, reliability), which may be suitable for transmissionvia different component carrier having different subcarrier spacingand/or bandwidth. FIG. 7B shows an example embodiment. A first componentcarrier may comprise a first number of subcarriers 706 with a firstsubcarrier spacing 709. A second component carrier may comprise a secondnumber of subcarriers 707 with a second subcarrier spacing 710. A thirdcomponent carrier may comprise a third number of subcarriers 708 with athird subcarrier spacing 711. Carriers in a multicarrier OFDMcommunication system may be contiguous carriers, non-contiguouscarriers, or a combination of both contiguous and non-contiguouscarriers.

FIG. 8 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present disclosure. In an example, a carrier mayhave a transmission bandwidth 801. In an example, a resource grid may bein a structure of frequency domain 802 and time domain 803. In anexample, a resource grid may comprise a first number of OFDM symbols ina subframe and a second number of resource blocks, starting from acommon resource block indicated by higher-layer signaling (e.g. RRCsignaling), for a transmission numerology and a carrier. In an example,in a resource grid, a resource unit identified by a subcarrier index anda symbol index may be a resource element 805. In an example, a subframemay comprise a first number of OFDM symbols 807 depending on anumerology associated with a carrier. For example, when a subcarrierspacing of a numerology of a carrier is 15 KHz, a subframe may have 14OFDM symbols for a carrier. When a subcarrier spacing of a numerology is30 KHz, a subframe may have 28 OFDM symbols. When a subcarrier spacingof a numerology is 60 Khz, a subframe may have 56 OFDM symbols, etc. Inan example, a second number of resource blocks comprised in a resourcegrid of a carrier may depend on a bandwidth and a numerology of thecarrier.

As shown in FIG. 8, a resource block 806 may comprise 12 subcarriers. Inan example, multiple resource blocks may be grouped into a ResourceBlock Group (RBG) 804. In an example, a size of a RBG may depend on atleast one of: a RRC message indicating a RBG size configuration; a sizeof a carrier bandwidth; or a size of a bandwidth part of a carrier. Inan example, a carrier may comprise multiple bandwidth parts. A firstbandwidth part of a carrier may have different frequency location and/orbandwidth from a second bandwidth part of the carrier.

In an example, a gNB may transmit a downlink control informationcomprising a downlink or uplink resource block assignment to a wirelessdevice. A base station may transmit to or receive from, a wirelessdevice, data packets (e.g. transport blocks) scheduled and transmittedvia one or more resource blocks and one or more slots according toparameters in a downlink control information and/or RRC message(s). Inan example, a starting symbol relative to a first slot of the one ormore slots may be indicated to the wireless device. In an example, a gNBmay transmit to or receive from, a wireless device, data packetsscheduled on one or more RBGs and one or more slots.

In an example, a gNB may transmit a downlink control informationcomprising a downlink assignment to a wireless device via one or morePDCCHs. The downlink assignment may comprise parameters indicating atleast modulation and coding format; resource allocation; and/or HARQinformation related to DL-SCH. In an example, a resource allocation maycomprise parameters of resource block allocation; and/or slotallocation. In an example, a gNB may dynamically allocate resources to awireless device via a Cell-Radio Network Temporary Identifier (C-RNTI)on one or more PDCCHs. The wireless device may monitor the one or morePDCCHs in order to find possible allocation when its downlink receptionis enabled. The wireless device may receive one or more downlink datapackage on one or more PDSCH scheduled by the one or more PDCCHs, whensuccessfully detecting the one or more PDCCHs.

In an example, a gNB may allocate Configured Scheduling (CS) resourcesfor down link transmission to a wireless device. The base station maytransmit one or more RRC messages indicating a periodicity of the CSgrant. The base station may transmit a DCI via a PDCCH addressed to aConfigured Scheduling-RNTI (CS-RNTI) activating the CS resources. TheDCI may comprise parameters indicating that the downlink grant is a CSgrant. The CS grant may be implicitly reused according to theperiodicity defined by the one or more RRC messages, until deactivated.

In an example, a gNB may transmit a downlink control informationcomprising an uplink grant to a wireless device via one or more PDCCHs.The uplink grant may comprise parameters indicating at least modulationand coding format; resource allocation; and/or HARQ information relatedto UL-SCH. In an example, a resource allocation may comprise parametersof resource block allocation; and/or slot allocation. In an example, agNB may dynamically allocate resources to a wireless device via a C-RNTIon one or more PDCCHs. The wireless device may monitor the one or morePDCCHs in order to find possible resource allocation. The wirelessdevice may transmit one or more uplink data package via one or morePUSCH scheduled by the one or more PDCCHs, when successfully detectingthe one or more PDCCHs.

In an example, a gNB may allocate CS resources for uplink datatransmission to a wireless device. The base station may transmit one ormore RRC messages indicating a periodicity of the CS grant. The basestation may transmit a DCI via a PDCCH addressed to a CS-RNTI activatingthe CS resources. The DCI may comprise parameters indicating that theuplink grant is a CS grant. The CS grant may be implicitly reusedaccording to the periodicity defined by the one or more RRC message,until deactivated.

In an example, a base station may transmit DCI/control signaling viaPDCCH. The DCI may take a format in a plurality of formats. A DCI maycomprise downlink and/or uplink scheduling information (e.g., resourceallocation information, HARQ related parameters, MCS), request for CSI(e.g., aperiodic CQI reports), request for SRS, uplink power controlcommands for one or more cells, one or more timing information (e.g., TBtransmission/reception timing, HARQ feedback timing, etc.), etc. In anexample, a DCI may indicate an uplink grant comprising transmissionparameters for one or more transport blocks. In an example, a DCI mayindicate downlink assignment indicating parameters for receiving one ormore transport blocks. In an example, a DCI may be used by base stationto initiate a contention-free random access at the wireless device. Inan example, the base station may transmit a DCI comprising slot formatindicator (SFI) notifying a slot format. In an example, the base stationmay transmit a DCI comprising pre-emption indication notifying thePRB(s) and/or OFDM symbol(s) where a UE may assume no transmission isintended for the UE. In an example, the base station may transmit a DCIfor group power control of PUCCH or PUSCH or SRS. In an example, a DCImay correspond to an RNTI. In an example, the wireless device may obtainan RNTI in response to completing the initial access (e.g., C-RNTI). Inan example, the base station may configure an RNTI for the wireless(e.g., CS-RNTI, TPC-CS-RNTI, TPC-PUCCH-RNTI, TPC-PUSCH-RNTI,TPC-SRS-RNTI). In an example, the wireless device may compute an RNTI(e.g., the wireless device may compute RA-RNTI based on resources usedfor transmission of a preamble). In an example, an RNTI may have apre-configured value (e.g., P-RNTI or SI-RNTI). In an example, awireless device may monitor a group common search space which may beused by base station for transmitting DCIs that are intended for a groupof UEs. In an example, a group common DCI may correspond to an RNTIwhich is commonly configured for a group of UEs. In an example, awireless device may monitor a UE-specific search space. In an example, aUE specific DCI may correspond to an RNTI configured for the wirelessdevice.

A NR system may support a single beam operation and/or a multi-beamoperation. In a multi-beam operation, a base station may perform adownlink beam sweeping to provide coverage for common control channelsand/or downlink SS blocks, which may comprise at least a PSS, a SSS,and/or PBCH. A wireless device may measure quality of a beam pair linkusing one or more RSs. One or more SS blocks, or one or more CSI-RSresources, associated with a CSI-RS resource index (CRI), or one or moreDM-RSs of PBCH, may be used as RS for measuring quality of a beam pairlink. Quality of a beam pair link may be defined as a reference signalreceived power (RSRP) value, or a reference signal received quality(RSRQ) value, and/or a CSI value measured on RS resources. The basestation may indicate whether an RS resource, used for measuring a beampair link quality, is quasi-co-located (QCLed) with DM-RSs of a controlchannel. A RS resource and DM-RSs of a control channel may be calledQCLed when a channel characteristics from a transmission on an RS to awireless device, and that from a transmission on a control channel to awireless device, are similar or same under a configured criterion. In amulti-beam operation, a wireless device may perform an uplink beamsweeping to access a cell.

In an example, a wireless device may be configured to monitor PDCCH onone or more beam pair links simultaneously depending on a capability ofa wireless device. This may increase robustness against beam pair linkblocking. A base station may transmit one or more messages to configurea wireless device to monitor PDCCH on one or more beam pair links indifferent PDCCH OFDM symbols. For example, a base station may transmithigher layer signaling (e.g. RRC signaling) or MAC CE comprisingparameters related to the Rx beam setting of a wireless device formonitoring PDCCH on one or more beam pair links. A base station maytransmit indication of spatial QCL assumption between an DL RS antennaport(s) (for example, cell-specific CSI-RS, or wireless device-specificCSI-RS, or SS block, or PBCH with or without DM-RSs of PBCH), and DL RSantenna port(s) for demodulation of DL control channel Signaling forbeam indication for a PDCCH may be MAC CE signaling, or RRC signaling,or DCI signaling, or specification-transparent and/or implicit method,and combination of these signaling methods.

For reception of unicast DL data channel, a base station may indicatespatial QCL parameters between DL RS antenna port(s) and DM-RS antennaport(s) of DL data channel. The base station may transmit DCI (e.g.downlink grants) comprising information indicating the RS antennaport(s). The information may indicate RS antenna port(s) which may beQCL-ed with the DM-RS antenna port(s). Different set of DM-RS antennaport(s) for a DL data channel may be indicated as QCL with different setof the RS antenna port(s).

FIG. 9A is an example of beam sweeping in a DL channel. In anRRC_INACTIVE state or RRC_IDLE state, a wireless device may assume thatSS blocks form an SS burst 940, and an SS burst set 950. The SS burstset 950 may have a given periodicity. For example, in a multi-beamoperation, a base station 120 may transmit SS blocks in multiple beams,together forming a SS burst 940. One or more SS blocks may betransmitted on one beam. If multiple SS bursts 940 are transmitted withmultiple beams, SS bursts together may form SS burst set 950.

A wireless device may further use CSI-RS in the multi-beam operation forestimating a beam quality of a links between a wireless device and abase station. A beam may be associated with a CSI-RS. For example, awireless device may, based on a RSRP measurement on CSI-RS, report abeam index, as indicated in a CRI for downlink beam selection, andassociated with a RSRP value of a beam. A CSI-RS may be transmitted on aCSI-RS resource including at least one of one or more antenna ports, oneor more time or frequency radio resources. A CSI-RS resource may beconfigured in a cell-specific way by common RRC signaling, or in awireless device-specific way by dedicated RRC signaling, and/or L1/L2signaling. Multiple wireless devices covered by a cell may measure acell-specific CSI-RS resource. A dedicated subset of wireless devicescovered by a cell may measure a wireless device-specific CSI-RSresource.

A CSI-RS resource may be transmitted periodically, or using aperiodictransmission, or using a multi-shot or semi-persistent transmission. Forexample, in a periodic transmission in FIG. 9A, a base station 120 maytransmit configured CSI-RS resources 940 periodically using a configuredperiodicity in a time domain. In an aperiodic transmission, a configuredCSI-RS resource may be transmitted in a dedicated time slot. In amulti-shot or semi-persistent transmission, a configured CSI-RS resourcemay be transmitted within a configured period. Beams used for CSI-RStransmission may have different beam width than beams used for SS-blockstransmission.

FIG. 9B is an example of a beam management procedure in an example newradio network. A base station 120 and/or a wireless device 110 mayperform a downlink L1/L2 beam management procedure. One or more of thefollowing downlink L1/L2 beam management procedures may be performedwithin one or more wireless devices 110 and one or more base stations120. In an example, a P-1 procedure 910 may be used to enable thewireless device 110 to measure one or more Transmission (Tx) beamsassociated with the base station 120 to support a selection of a firstset of Tx beams associated with the base station 120 and a first set ofRx beam(s) associated with a wireless device 110. For beamforming at abase station 120, a base station 120 may sweep a set of different TXbeams. For beamforming at a wireless device 110, a wireless device 110may sweep a set of different Rx beams. In an example, a P-2 procedure920 may be used to enable a wireless device 110 to measure one or moreTx beams associated with a base station 120 to possibly change a firstset of Tx beams associated with a base station 120. A P-2 procedure 920may be performed on a possibly smaller set of beams for beam refinementthan in the P-1 procedure 910. A P-2 procedure 920 may be a special caseof a P-1 procedure 910. In an example, a P-3 procedure 930 may be usedto enable a wireless device 110 to measure at least one Tx beamassociated with a base station 120 to change a first set of Rx beamsassociated with a wireless device 110.

A wireless device 110 may transmit one or more beam management reportsto a base station 120. In one or more beam management reports, awireless device 110 may indicate some beam pair quality parameters,comprising at least, one or more beam identifications; RSRP; PrecodingMatrix Indicator (PMI)/Channel Quality Indicator (CQI)/Rank Indicator(RI) of a subset of configured beams. Based on one or more beammanagement reports, a base station 120 may transmit to a wireless device110 a signal indicating that one or more beam pair links are one or moreserving beams. A base station 120 may transmit PDCCH and PDSCH for awireless device 110 using one or more serving beams.

In an example embodiment, new radio network may support a BandwidthAdaptation (BA). In an example, receive and/or transmit bandwidthsconfigured by an UE employing a BA may not be large. For example, areceive and/or transmit bandwidths may not be as large as a bandwidth ofa cell. Receive and/or transmit bandwidths may be adjustable. Forexample, a UE may change receive and/or transmit bandwidths, e.g., toshrink during period of low activity to save power. For example, a UEmay change a location of receive and/or transmit bandwidths in afrequency domain, e.g. to increase scheduling flexibility. For example,a UE may change a subcarrier spacing, e.g. to allow different services.

In an example embodiment, a subset of a total cell bandwidth of a cellmay be referred to as a Bandwidth Part (BWP). A base station mayconfigure a UE with one or more BWPs to achieve a BA. For example, abase station may indicate, to a UE, which of the one or more(configured) BWPs is an active BWP.

FIG. 10 is an example diagram of 3 BWPs configured: BWP1 (1010 and 1050)with a width of 40 MHz and subcarrier spacing of 15 kHz; BWP2 (1020 and1040) with a width of 10 MHz and subcarrier spacing of 15 kHz; BWP3 1030with a width of 20 MHz and subcarrier spacing of 60 kHz.

In an example, a UE, configured for operation in one or more BWPs of acell, may be configured by one or more higher layers (e.g. RRC layer)for a cell a set of one or more BWPs (e.g., at most four BWPs) forreceptions by the UE (DL BWP set) in a DL bandwidth by at least oneparameter DL-BWP and a set of one or more BWPs (e.g., at most four BWPs)for transmissions by a UE (UL BWP set) in an UL bandwidth by at leastone parameter UL-BWP for a cell.

To enable BA on the PCell, a base station may configure a UE with one ormore UL and DL BWP pairs. To enable BA on SCells (e.g., in case of CA),a base station may configure a UE at least with one or more DL BWPs(e.g., there may be none in an UL).

In an example, an initial active DL BWP may be defined by at least oneof a location and number of contiguous PRBs, a subcarrier spacing, or acyclic prefix, for a control resource set for at least one common searchspace. For operation on the PCell, one or more higher layer parametersmay indicate at least one initial UL BWP for a random access procedure.If a UE is configured with a secondary carrier on a primary cell, the UEmay be configured with an initial BWP for random access procedure on asecondary carrier.

In an example, for unpaired spectrum operation, a UE may expect that acenter frequency for a DL BWP may be same as a center frequency for a ULBWP.

For example, for a DL BWP or an UL BWP in a set of one or more DL BWPsor one or more UL BWPs, respectively, a base station may semi-staticallyconfigure a UE for a cell with one or more parameters indicating atleast one of following: a subcarrier spacing; a cyclic prefix; a numberof contiguous PRBs; an index in the set of one or more DL BWPs and/orone or more UL BWPs; a link between a DL BWP and an UL BWP from a set ofconfigured DL BWPs and UL BWPs; a DCI detection to a PDSCH receptiontiming; a PDSCH reception to a HARQ-ACK transmission timing value; a DCIdetection to a PUSCH transmission timing value; an offset of a first PRBof a DL bandwidth or an UL bandwidth, respectively, relative to a firstPRB of a bandwidth.

In an example, for a DL BWP in a set of one or more DL BWPs on a PCell,a base station may configure a UE with one or more control resource setsfor at least one type of common search space and/or one UE-specificsearch space. For example, a base station may not configure a UE withouta common search space on a PCell, or on a PSCell, in an active DL BWP.

For an UL BWP in a set of one or more UL BWPs, a base station mayconfigure a UE with one or more resource sets for one or more PUCCHtransmissions.

In an example, if a DCI comprises a BWP indicator field, a BWP indicatorfield value may indicate an active DL BWP, from a configured DL BWP set,for one or more DL receptions. If a DCI comprises a BWP indicator field,a BWP indicator field value may indicate an active UL BWP, from aconfigured UL BWP set, for one or more UL transmissions.

In an example, for a PCell, a base station may semi-statically configurea UE with a default DL BWP among configured DL BWPs. If a UE is notprovided a default DL BWP, a default BWP may be an initial active DLBWP.

In an example, a base station may configure a UE with a timer value fora PCell. For example, a UE may start a timer, referred to as BWPinactivity timer, when a UE detects a DCI indicating an active DL BWP,other than a default DL BWP, for a paired spectrum operation or when aUE detects a DCI indicating an active DL BWP or UL BWP, other than adefault DL BWP or UL BWP, for an unpaired spectrum operation. The UE mayincrement the timer by an interval of a first value (e.g., the firstvalue may be 1 millisecond or 0.5 milliseconds) if the UE does notdetect a DCI during the interval for a paired spectrum operation or foran unpaired spectrum operation. In an example, the timer may expire whenthe timer is equal to the timer value. A UE may switch to the default DLBWP from an active DL BWP when the timer expires.

In an example, a base station may semi-statically configure a UE withone or more BWPs. A UE may switch an active BWP from a first BWP to asecond BWP in response to receiving a DCI indicating the second BWP asan active BWP and/or in response to an expiry of BWP inactivity timer(for example, the second BWP may be a default BWP). For example, FIG. 10is an example diagram of 3 BWPs configured, BWP1 (1010 and 1050), BWP2(1020 and 1040), and BWP3 (1030). BWP2 (1020 and 1040) may be a defaultBWP. BWP1 (1010) may be an initial active BWP. In an example, a UE mayswitch an active BWP from BWP1 1010 to BWP2 1020 in response to anexpiry of BWP inactivity timer. For example, a UE may switch an activeBWP from BWP2 1020 to BWP3 1030 in response to receiving a DCIindicating BWP3 1030 as an active BWP. Switching an active BWP from BWP31030 to BWP2 1040 and/or from BWP2 1040 to BWP1 1050 may be in responseto receiving a DCI indicating an active BWP and/or in response to anexpiry of BWP inactivity timer.

In an example, if a UE is configured for a secondary cell with a defaultDL BWP among configured DL BWPs and a timer value, UE procedures on asecondary cell may be same as on a primary cell using the timer valuefor the secondary cell and the default DL BWP for the secondary cell.

In an example, if a base station configures a UE with a first active DLBWP and a first active UL BWP on a secondary cell or carrier, a UE mayemploy an indicated DL BWP and an indicated UL BWP on a secondary cellas a respective first active DL BWP and first active UL BWP on asecondary cell or carrier.

FIG. 11A and FIG. 11B show packet flows employing a multi connectivity(e.g. dual connectivity, multi connectivity, tight interworking, and/orthe like). FIG. 11A is an example diagram of a protocol structure of awireless device 110 (e.g. UE) with CA and/or multi connectivity as peran aspect of an embodiment. FIG. 11B is an example diagram of a protocolstructure of multiple base stations with CA and/or multi connectivity asper an aspect of an embodiment. The multiple base stations may comprisea master node, MN 1130 (e.g. a master node, a master base station, amaster gNB, a master eNB, and/or the like) and a secondary node, SN 1150(e.g. a secondary node, a secondary base station, a secondary gNB, asecondary eNB, and/or the like). A master node 1130 and a secondary node1150 may co-work to communicate with a wireless device 110.

When multi connectivity is configured for a wireless device 110, thewireless device 110, which may support multiple reception/transmissionfunctions in an RRC connected state, may be configured to utilize radioresources provided by multiple schedulers of a multiple base stations.Multiple base stations may be inter-connected via a non-ideal or idealbackhaul (e.g. Xn interface, X2 interface, and/or the like). A basestation involved in multi connectivity for a certain wireless device mayperform at least one of two different roles: a base station may eitheract as a master base station or as a secondary base station. In multiconnectivity, a wireless device may be connected to one master basestation and one or more secondary base stations. In an example, a masterbase station (e.g. the MN 1130) may provide a master cell group (MCG)comprising a primary cell and/or one or more secondary cells for awireless device (e.g. the wireless device 110). A secondary base station(e.g. the SN 1150) may provide a secondary cell group (SCG) comprising aprimary secondary cell (PSCell) and/or one or more secondary cells for awireless device (e.g. the wireless device 110).

In multi connectivity, a radio protocol architecture that a beareremploys may depend on how a bearer is setup. In an example, threedifferent type of bearer setup options may be supported: an MCG bearer,an SCG bearer, and/or a split bearer. A wireless device mayreceive/transmit packets of an MCG bearer via one or more cells of theMCG, and/or may receive/transmits packets of an SCG bearer via one ormore cells of an SCG. Multi-connectivity may also be described as havingat least one bearer configured to use radio resources provided by thesecondary base station. Multi-connectivity may or may not beconfigured/implemented in some of the example embodiments.

In an example, a wireless device (e.g. Wireless Device 110) may transmitand/or receive: packets of an MCG bearer via an SDAP layer (e.g. SDAP1110), a PDCP layer (e.g. NR PDCP 1111), an RLC layer (e.g. MN RLC1114), and a MAC layer (e.g. MN MAC 1118); packets of a split bearer viaan SDAP layer (e.g. SDAP 1110), a PDCP layer (e.g. NR PDCP 1112), one ofa master or secondary RLC layer (e.g. MN RLC 1115, SN RLC 1116), and oneof a master or secondary MAC layer (e.g. MN MAC 1118, SN MAC 1119);and/or packets of an SCG bearer via an SDAP layer (e.g. SDAP 1110), aPDCP layer (e.g. NR PDCP 1113), an RLC layer (e.g. SN RLC 1117), and aMAC layer (e.g. MN MAC 1119).

In an example, a master base station (e.g. MN 1130) and/or a secondarybase station (e.g. SN 1150) may transmit/receive: packets of an MCGbearer via a master or secondary node SDAP layer (e.g. SDAP 1120, SDAP1140), a master or secondary node PDCP layer (e.g. NR PDCP 1121, NR PDCP1142), a master node RLC layer (e.g. MN RLC 1124, MN RLC 1125), and amaster node MAC layer (e.g. MN MAC 1128); packets of an SCG bearer via amaster or secondary node SDAP layer (e.g. SDAP 1120, SDAP 1140), amaster or secondary node PDCP layer (e.g. NR PDCP 1122, NR PDCP 1143), asecondary node RLC layer (e.g. SN RLC 1146, SN RLC 1147), and asecondary node MAC layer (e.g. SN MAC 1148); packets of a split bearervia a master or secondary node SDAP layer (e.g. SDAP 1120, SDAP 1140), amaster or secondary node PDCP layer (e.g. NR PDCP 1123, NR PDCP 1141), amaster or secondary node RLC layer (e.g. MN RLC 1126, SN RLC 1144, SNRLC 1145, MN RLC 1127), and a master or secondary node MAC layer (e.g.MN MAC 1128, SN MAC 1148).

In multi connectivity, a wireless device may configure multiple MACentities: one MAC entity (e.g. MN MAC 1118) for a master base station,and other MAC entities (e.g. SN MAC 1119) for a secondary base station.In multi-connectivity, a configured set of serving cells for a wirelessdevice may comprise two subsets: an MCG comprising serving cells of amaster base station, and SCGs comprising serving cells of a secondarybase station. For an SCG, one or more of following configurations may beapplied: at least one cell of an SCG has a configured UL CC and at leastone cell of a SCG, named as primary secondary cell (PSCell, PCell ofSCG, or sometimes called PCell), is configured with PUCCH resources;when an SCG is configured, there may be at least one SCG bearer or oneSplit bearer; upon detection of a physical layer problem or a randomaccess problem on a PSCell, or a number of NR RLC retransmissions hasbeen reached associated with the SCG, or upon detection of an accessproblem on a PSCell during a SCG addition or a SCG change: an RRCconnection re-establishment procedure may not be triggered, ULtransmissions towards cells of an SCG may be stopped, a master basestation may be informed by a wireless device of a SCG failure type, forsplit bearer, a DL data transfer over a master base station may bemaintained; an NR RLC acknowledged mode (AM) bearer may be configuredfor a split bearer; PCell and/or PSCell may not be de-activated; PSCellmay be changed with a SCG change procedure (e.g. with security keychange and a RACH procedure); and/or a bearer type change between asplit bearer and a SCG bearer or simultaneous configuration of a SCG anda split bearer may or may not supported.

With respect to interaction between a master base station and asecondary base stations for multi-connectivity, one or more of thefollowing may be applied: a master base station and/or a secondary basestation may maintain RRM measurement configurations of a wirelessdevice; a master base station may (e.g. based on received measurementreports, traffic conditions, and/or bearer types) may decide to requesta secondary base station to provide additional resources (e.g. servingcells) for a wireless device; upon receiving a request from a masterbase station, a secondary base station may create/modify a containerthat may result in configuration of additional serving cells for awireless device (or decide that the secondary base station has noresource available to do so); for a UE capability coordination, a masterbase station may provide (a part of) an AS configuration and UEcapabilities to a secondary base station; a master base station and asecondary base station may exchange information about a UE configurationby employing of RRC containers (inter-node messages) carried via Xnmessages; a secondary base station may initiate a reconfiguration of thesecondary base station existing serving cells (e.g. PUCCH towards thesecondary base station); a secondary base station may decide which cellis a PSCell within a SCG; a master base station may or may not changecontent of RRC configurations provided by a secondary base station; incase of a SCG addition and/or a SCG SCell addition, a master basestation may provide recent (or the latest) measurement results for SCGcell(s); a master base station and secondary base stations may receiveinformation of SFN and/or subframe offset of each other from OAM and/orvia an Xn interface, (e.g. for a purpose of DRX alignment and/oridentification of a measurement gap). In an example, when adding a newSCG SCell, dedicated RRC signaling may be used for sending requiredsystem information of a cell as for CA, except for a SFN acquired from aMIB of a PSCell of a SCG.

FIG. 12 is an example diagram of a random access procedure. One or moreevents may trigger a random access procedure. For example, one or moreevents may be at least one of following: initial access from RRC_IDLE,RRC connection re-establishment procedure, handover, DL or UL dataarrival during RRC_CONNECTED when UL synchronization status isnon-synchronized, transition from RRC_Inactive, and/or request for othersystem information. For example, a PDCCH order, a MAC entity, and/or abeam failure indication may initiate a random access procedure.

In an example embodiment, a random access procedure may be at least oneof a contention based random access procedure and a contention freerandom access procedure. For example, a contention based random accessprocedure may comprise, one or more Msg 1 1220 transmissions, one ormore Msg2 1230 transmissions, one or more Msg3 1240 transmissions, andcontention resolution 1250. For example, a contention free random accessprocedure may comprise one or more Msg 1 1220 transmissions and one ormore Msg2 1230 transmissions.

In an example, a base station may transmit (e.g., unicast, multicast, orbroadcast), to a UE, a RACH configuration 1210 via one or more beams.The RACH configuration 1210 may comprise one or more parametersindicating at least one of following: available set of PRACH resourcesfor a transmission of a random access preamble, initial preamble power(e.g., random access preamble initial received target power), an RSRPthreshold for a selection of a SS block and corresponding PRACHresource, a power-ramping factor (e.g., random access preamble powerramping step), random access preamble index, a maximum number ofpreamble transmission, preamble group A and group B, a threshold (e.g.,message size) to determine the groups of random access preambles, a setof one or more random access preambles for system information requestand corresponding PRACH resource(s), if any, a set of one or more randomaccess preambles for beam failure recovery request and correspondingPRACH resource(s), if any, a time window to monitor RA response(s), atime window to monitor response(s) on beam failure recovery request,and/or a contention resolution timer.

In an example, the Msg1 1220 may be one or more transmissions of arandom access preamble. For a contention based random access procedure,a UE may select a SS block with a RSRP above the RSRP threshold. Ifrandom access preambles group B exists, a UE may select one or morerandom access preambles from a group A or a group B depending on apotential Msg3 1240 size. If a random access preambles group B does notexist, a UE may select the one or more random access preambles from agroup A. A UE may select a random access preamble index randomly (e.g.with equal probability or a normal distribution) from one or more randomaccess preambles associated with a selected group. If a base stationsemi-statically configures a UE with an association between randomaccess preambles and SS blocks, the UE may select a random accesspreamble index randomly with equal probability from one or more randomaccess preambles associated with a selected SS block and a selectedgroup.

For example, a UE may initiate a contention free random access procedurebased on a beam failure indication from a lower layer. For example, abase station may semi-statically configure a UE with one or morecontention free PRACH resources for beam failure recovery requestassociated with at least one of SS blocks and/or CSI-RSs. If at leastone of SS blocks with a RSRP above a first RSRP threshold amongstassociated SS blocks or at least one of CSI-RSs with a RSRP above asecond RSRP threshold amongst associated CSI-RSs is available, a UE mayselect a random access preamble index corresponding to a selected SSblock or CSI-RS from a set of one or more random access preambles forbeam failure recovery request.

For example, a UE may receive, from a base station, a random accesspreamble index via PDCCH or RRC for a contention free random accessprocedure. If a base station does not configure a UE with at least onecontention free PRACH resource associated with SS blocks or CSI-RS, theUE may select a random access preamble index. If a base stationconfigures a UE with one or more contention free PRACH resourcesassociated with SS blocks and at least one SS block with a RSRP above afirst RSRP threshold amongst associated SS blocks is available, the UEmay select the at least one SS block and select a random access preamblecorresponding to the at least one SS block. If a base station configuresa UE with one or more contention free PRACH resources associated withCSI-RSs and at least one CSI-RS with a RSRP above a second RSRPthreshold amongst the associated CSI-RSs is available, the UE may selectthe at least one CSI-RS and select a random access preamblecorresponding to the at least one CSI-RS.

A UE may perform one or more Msg1 1220 transmissions by transmitting theselected random access preamble. For example, if a UE selects an SSblock and is configured with an association between one or more PRACHoccasions and one or more SS blocks, the UE may determine an PRACHoccasion from one or more PRACH occasions corresponding to a selected SSblock. For example, if a UE selects a CSI-RS and is configured with anassociation between one or more PRACH occasions and one or more CSI-RSs,the UE may determine a PRACH occasion from one or more PRACH occasionscorresponding to a selected CSI-RS. A UE may transmit, to a basestation, a selected random access preamble via a selected PRACHoccasions. A UE may determine a transmit power for a transmission of aselected random access preamble at least based on an initial preamblepower and a power-ramping factor. A UE may determine a RA-RNTIassociated with a selected PRACH occasions in which a selected randomaccess preamble is transmitted. For example, a UE may not determine aRA-RNTI for a beam failure recovery request. A UE may determine anRA-RNTI at least based on an index of a first OFDM symbol and an indexof a first slot of a selected PRACH occasions, and/or an uplink carrierindex for a transmission of Msg1 1220.

In an example, a UE may receive, from a base station, a random accessresponse, Msg 2 1230. A UE may start a time window (e.g., ra-ResponseWindow) to monitor a random access response. For beam failure recoveryrequest, a base station may configure a UE with a different time window(e.g., bfr-ResponseWindow) to monitor response on beam failure recoveryrequest. For example, a UE may start a time window (e.g.,ra-ResponseWindow or bfr-ResponseWindow) at a start of a first PDCCHoccasion after a fixed duration of one or more symbols from an end of apreamble transmission. If a UE transmits multiple preambles, the UE maystart a time window at a start of a first PDCCH occasion after a fixedduration of one or more symbols from an end of a first preambletransmission. A UE may monitor a PDCCH of a cell for at least one randomaccess response identified by a RA-RNTI or for at least one response tobeam failure recovery request identified by a C-RNTI while a timer for atime window is running

In an example, a UE may consider a reception of random access responsesuccessful if at least one random access response comprises a randomaccess preamble identifier corresponding to a random access preambletransmitted by the UE. A UE may consider the contention free randomaccess procedure successfully completed if a reception of random accessresponse is successful. If a contention free random access procedure istriggered for a beam failure recovery request, a UE may consider acontention free random access procedure successfully complete if a PDCCHtransmission is addressed to a C-RNTI. In an example, if at least onerandom access response comprises a random access preamble identifier, aUE may consider the random access procedure successfully completed andmay indicate a reception of an acknowledgement for a system informationrequest to upper layers. If a UE has signaled multiple preambletransmissions, the UE may stop transmitting remaining preambles (if any)in response to a successful reception of a corresponding random accessresponse.

In an example, a UE may perform one or more Msg 3 1240 transmissions inresponse to a successful reception of random access response (e.g., fora contention based random access procedure). A UE may adjust an uplinktransmission timing based on a timing advanced command indicated by arandom access response and may transmit one or more transport blocksbased on an uplink grant indicated by a random access response.Subcarrier spacing for PUSCH transmission for Msg3 1240 may be providedby at least one higher layer (e.g. RRC) parameter. A UE may transmit arandom access preamble via PRACH and Msg3 1240 via PUSCH on a same cell.A base station may indicate an UL BWP for a PUSCH transmission of Msg31240 via system information block. A UE may employ HARQ for aretransmission of Msg 3 1240.

In an example, multiple UEs may perform Msg 1 1220 by transmitting asame preamble to a base station and receive, from the base station, asame random access response comprising an identity (e.g., TC-RNTI).Contention resolution 1250 may ensure that a UE does not incorrectly usean identity of another UE. For example, contention resolution 1250 maybe based on C-RNTI on PDCCH or a UE contention resolution identity onDL-SCH. For example, if a base station assigns a C-RNTI to a UE, the UEmay perform contention resolution 1250 based on a reception of a PDCCHtransmission that is addressed to the C-RNTI. In response to detectionof a C-RNTI on a PDCCH, a UE may consider contention resolution 1250successful and may consider a random access procedure successfullycompleted. If a UE has no valid C-RNTI, a contention resolution may beaddressed by employing a TC-RNTI. For example, if a MAC PDU issuccessfully decoded and a MAC PDU comprises a UE contention resolutionidentity MAC CE that matches the CCCH SDU transmitted in Msg3 1250, a UEmay consider the contention resolution 1250 successful and may considerthe random access procedure successfully completed.

FIG. 13 is an example structure for MAC entities as per an aspect of anembodiment. In an example, a wireless device may be configured tooperate in a multi-connectivity mode. A wireless device in RRC_CONNECTEDwith multiple RX/TX may be configured to utilize radio resourcesprovided by multiple schedulers located in a plurality of base stations.The plurality of base stations may be connected via a non-ideal or idealbackhaul over the Xn interface. In an example, a base station in aplurality of base stations may act as a master base station or as asecondary base station. A wireless device may be connected to one masterbase station and one or more secondary base stations. A wireless devicemay be configured with multiple MAC entities, e.g. one MAC entity formaster base station, and one or more other MAC entities for secondarybase station(s). In an example, a configured set of serving cells for awireless device may comprise two subsets: an MCG comprising servingcells of a master base station, and one or more SCGs comprising servingcells of a secondary base station(s). FIG. 13 illustrates an examplestructure for MAC entities when MCG and SCG are configured for awireless device.

In an example, at least one cell in a SCG may have a configured UL CC,wherein a cell of at least one cell may be called PSCell or PCell ofSCG, or sometimes may be simply called PCell. A PSCell may be configuredwith PUCCH resources. In an example, when a SCG is configured, there maybe at least one SCG bearer or one split bearer. In an example, upondetection of a physical layer problem or a random access problem on aPSCell, or upon reaching a number of RLC retransmissions associated withthe SCG, or upon detection of an access problem on a PSCell during a SCGaddition or a SCG change: an RRC connection re-establishment proceduremay not be triggered, UL transmissions towards cells of an SCG may bestopped, a master base station may be informed by a UE of a SCG failuretype and DL data transfer over a master base station may be maintained.

In an example, a MAC sublayer may provide services such as data transferand radio resource allocation to upper layers (e.g. 1310 or 1320). A MACsublayer may comprise a plurality of MAC entities (e.g. 1350 and 1360).A MAC sublayer may provide data transfer services on logical channels.To accommodate different kinds of data transfer services, multiple typesof logical channels may be defined. A logical channel may supporttransfer of a particular type of information. A logical channel type maybe defined by what type of information (e.g., control or data) istransferred. For example, BCCH, PCCH, CCCH and DCCH may be controlchannels and DTCH may be a traffic channel. In an example, a first MACentity (e.g. 1310) may provide services on PCCH, BCCH, CCCH, DCCH, DTCHand MAC control elements. In an example, a second MAC entity (e.g. 1320)may provide services on BCCH, DCCH, DTCH and MAC control elements.

A MAC sublayer may expect from a physical layer (e.g. 1330 or 1340)services such as data transfer services, signaling of HARQ feedback,signaling of scheduling request or measurements (e.g. CQI). In anexample, in dual connectivity, two MAC entities may be configured for awireless device: one for MCG and one for SCG. A MAC entity of wirelessdevice may handle a plurality of transport channels. In an example, afirst MAC entity may handle first transport channels comprising a PCCHof MCG, a first BCH of MCG, one or more first DL-SCHs of MCG, one ormore first UL-SCHs of MCG and one or more first RACHs of MCG. In anexample, a second MAC entity may handle second transport channelscomprising a second BCH of SCG, one or more second DL-SCHs of SCG, oneor more second UL-SCHs of SCG and one or more second RACHs of SCG.

In an example, if a MAC entity is configured with one or more SCells,there may be multiple DL-SCHs and there may be multiple UL-SCHs as wellas multiple RACHs per MAC entity. In an example, there may be one DL-SCHand UL-SCH on a SpCell. In an example, there may be one DL-SCH, zero orone UL-SCH and zero or one RACH for an SCell. A DL-SCH may supportreceptions using different numerologies and/or TTI duration within a MACentity. A UL-SCH may also support transmissions using differentnumerologies and/or TTI duration within the MAC entity.

In an example, a MAC sublayer may support different functions and maycontrol these functions with a control (e.g. 1355 or 1365) element.Functions performed by a MAC entity may comprise mapping between logicalchannels and transport channels (e.g., in uplink or downlink),multiplexing (e.g. 1352 or 1362) of MAC SDUs from one or differentlogical channels onto transport blocks (TB) to be delivered to thephysical layer on transport channels (e.g., in uplink), demultiplexing(e.g. 1352 or 1362) of MAC SDUs to one or different logical channelsfrom transport blocks (TB) delivered from the physical layer ontransport channels (e.g., in downlink), scheduling information reporting(e.g., in uplink), error correction through HARQ in uplink or downlink(e.g. 1363), and logical channel prioritization in uplink (e.g. 1351 or1361). A MAC entity may handle a random access process (e.g. 1354 or1364).

FIG. 14 is an example diagram of a RAN architecture comprising one ormore base stations. In an example, a protocol stack (e.g. RRC, SDAP,PDCP, RLC, MAC, and PHY) may be supported at a node. A base station(e.g. 120A or 120B) may comprise a base station central unit (CU) (e.g.gNB-CU 1420A or 1420B) and at least one base station distributed unit(DU) (e.g. gNB-DU 1430A, 1430B, 1430C, or 1430D) if a functional splitis configured. Upper protocol layers of a base station may be located ina base station CU, and lower layers of the base station may be locatedin the base station DUs. An F1 interface (e.g. CU-DU interface)connecting a base station CU and base station DUs may be an ideal ornon-ideal backhaul. F1-C may provide a control plane connection over anF1 interface, and F1-U may provide a user plane connection over the F1interface. In an example, an Xn interface may be configured between basestation CUs.

In an example, a base station CU may comprise an RRC function, an SDAPlayer, and a PDCP layer, and base station DUs may comprise an RLC layer,a MAC layer, and a PHY layer. In an example, various functional splitoptions between a base station CU and base station DUs may be possibleby locating different combinations of upper protocol layers (RANfunctions) in a base station CU and different combinations of lowerprotocol layers (RAN functions) in base station DUs. A functional splitmay support flexibility to move protocol layers between a base stationCU and base station DUs depending on service requirements and/or networkenvironments.

In an example, functional split options may be configured per basestation, per base station CU, per base station DU, per UE, per bearer,per slice, or with other granularities. In per base station CU split, abase station CU may have a fixed split option, and base station DUs maybe configured to match a split option of a base station CU. In per basestation DU split, a base station DU may be configured with a differentsplit option, and a base station CU may provide different split optionsfor different base station DUs. In per UE split, a base station (basestation CU and at least one base station DUs) may provide differentsplit options for different wireless devices. In per bearer split,different split options may be utilized for different bearers. In perslice splice, different split options may be applied for differentslices.

FIG. 15 is an example diagram showing RRC state transitions of awireless device. In an example, a wireless device may be in at least oneRRC state among an RRC connected state (e.g. RRC Connected 1530,RRC_Connected), an RRC idle state (e.g. RRC Idle 1510, RRC_Idle), and/oran RRC inactive state (e.g. RRC Inactive 1520, RRC_Inactive). In anexample, in an RRC connected state, a wireless device may have at leastone RRC connection with at least one base station (e.g. gNB and/or eNB),which may have a UE context of the wireless device. A UE context (e.g. awireless device context) may comprise at least one of an access stratumcontext, one or more radio link configuration parameters, bearer (e.g.data radio bearer (DRB), signaling radio bearer (SRB), logical channel,QoS flow, PDU session, and/or the like) configuration information,security information, PHY/MAC/RLC/PDCP/SDAP layer configurationinformation, and/or the like configuration information for a wirelessdevice. In an example, in an RRC idle state, a wireless device may nothave an RRC connection with a base station, and a UE context of awireless device may not be stored in a base station. In an example, inan RRC inactive state, a wireless device may not have an RRC connectionwith a base station. A UE context of a wireless device may be stored ina base station, which may be called as an anchor base station (e.g. lastserving base station).

In an example, a wireless device may transition a UE RRC state betweenan RRC idle state and an RRC connected state in both ways (e.g.connection release 1540 or connection establishment 1550; or connectionreestablishment) and/or between an RRC inactive state and an RRCconnected state in both ways (e.g. connection inactivation 1570 orconnection resume 1580). In an example, a wireless device may transitionits RRC state from an RRC inactive state to an RRC idle state (e.g.connection release 1560).

In an example, an anchor base station may be a base station that maykeep a UE context (a wireless device context) of a wireless device atleast during a time period that a wireless device stays in a RANnotification area (RNA) of an anchor base station, and/or that awireless device stays in an RRC inactive state. In an example, an anchorbase station may be a base station that a wireless device in an RRCinactive state was lastly connected to in a latest RRC connected stateor that a wireless device lastly performed an RNA update procedure in.In an example, an RNA may comprise one or more cells operated by one ormore base stations. In an example, a base station may belong to one ormore RNAs. In an example, a cell may belong to one or more RNAs.

In an example, a wireless device may transition a UE RRC state from anRRC connected state to an RRC inactive state in a base station. Awireless device may receive RNA information from the base station. RNAinformation may comprise at least one of an RNA identifier, one or morecell identifiers of one or more cells of an RNA, a base stationidentifier, an IP address of the base station, an AS context identifierof the wireless device, a resume identifier, and/or the like.

In an example, an anchor base station may broadcast a message (e.g. RANpaging message) to base stations of an RNA to reach to a wireless devicein an RRC inactive state, and/or the base stations receiving the messagefrom the anchor base station may broadcast and/or multicast anothermessage (e.g. paging message) to wireless devices in their coveragearea, cell coverage area, and/or beam coverage area associated with theRNA through an air interface.

In an example, when a wireless device in an RRC inactive state movesinto a new RNA, the wireless device may perform an RNA update (RNAU)procedure, which may comprise a random access procedure by the wirelessdevice and/or a UE context retrieve procedure. A UE context retrieve maycomprise: receiving, by a base station from a wireless device, a randomaccess preamble; and fetching, by a base station, a UE context of thewireless device from an old anchor base station. Fetching may comprise:sending a retrieve UE context request message comprising a resumeidentifier to the old anchor base station and receiving a retrieve UEcontext response message comprising the UE context of the wirelessdevice from the old anchor base station.

In an example embodiment, a wireless device in an RRC inactive state mayselect a cell to camp on based on at least a on measurement results forone or more cells, a cell where a wireless device may monitor an RNApaging message and/or a core network paging message from a base station.In an example, a wireless device in an RRC inactive state may select acell to perform a random access procedure to resume an RRC connectionand/or to transmit one or more packets to a base station (e.g. to anetwork). In an example, if a cell selected belongs to a different RNAfrom an RNA for a wireless device in an RRC inactive state, the wirelessdevice may initiate a random access procedure to perform an RNA updateprocedure. In an example, if a wireless device in an RRC inactive statehas one or more packets, in a buffer, to transmit to a network, thewireless device may initiate a random access procedure to transmit oneor more packets to a base station of a cell that the wireless deviceselects. A random access procedure may be performed with two messages(e.g. 2 stage random access) and/or four messages (e.g. 4 stage randomaccess) between the wireless device and the base station.

In an example embodiment, a base station receiving one or more uplinkpackets from a wireless device in an RRC inactive state may fetch a UEcontext of a wireless device by transmitting a retrieve UE contextrequest message for the wireless device to an anchor base station of thewireless device based on at least one of an AS context identifier, anRNA identifier, a base station identifier, a resume identifier, and/or acell identifier received from the wireless device. In response tofetching a UE context, a base station may transmit a path switch requestfor a wireless device to a core network entity (e.g. AMF, MME, and/orthe like). A core network entity may update a downlink tunnel endpointidentifier for one or more bearers established for the wireless devicebetween a user plane core network entity (e.g. UPF, S-GW, and/or thelike) and a RAN node (e.g. the base station), e.g. changing a downlinktunnel endpoint identifier from an address of the anchor base station toan address of the base station.

A gNB may communicate with a wireless device via a wireless networkemploying one or more new radio technologies. The one or more radiotechnologies may comprise at least one of: multiple technologies relatedto physical layer; multiple technologies related to medium accesscontrol layer; and/or multiple technologies related to radio resourcecontrol layer. Example embodiments of enhancing the one or more radiotechnologies may improve performance of a wireless network. Exampleembodiments may increase the system throughput, or data rate oftransmission. Example embodiments may reduce battery consumption of awireless device. Example embodiments may improve latency of datatransmission between a gNB and a wireless device. Example embodimentsmay improve network coverage of a wireless network. Example embodimentsmay improve transmission efficiency of a wireless network.

Random access (RA) procedures may be used to establish communicationsbetween a wireless device and a base station in a cell. A four-step RAprocedure in FIG. 12 may have an associated latency, e.g., which may bea minimum of fourteen transmission time intervals (TTI). As an example,3GPP TR 38.804 v14.0.0 indicates a minimum latency of fourteen TTIscomprising, e.g., 3 TTIs after a message from step 1 (e.g., Msg1 1220)of a four-step RA procedure, 1 TTI for a message from step 2 (e.g., Msg21230) of a four-step RA procedure, 5 TTIs after the message from step 2,1 TTI for a message from step 3 (e.g., Msg 3 1240) of a four-step RAprocedure, 3 TTIs after the message from step 3, and 1 TTI for a messagefrom step 4 (e.g., contention Resolution 1250) of a four-step procedure(e.g., 3+1+5+1+3+1=14). Reducing the number of steps in an RA proceduremay reduce latency. By using parallel transmissions, a four-step RAprocedure may be reduced to a two-step RA procedure. A two-step RAprocedure may have an associated latency, e.g., which may be a minimumof four TTIs and which may be less than an associated latency for afour-step RA procedure. As an example, 3GPP TR 38.804 v14.0.0 indicatesa minimum latency of four TTIs comprising, e.g., 3 TTIs after a messagefrom step 1 of a two-step RA procedure and 1 TTI for a message from step2 of a two-step RA procedure.

FIG. 16 is an example of a two-step RA procedure that may comprise anuplink (UL) transmission of a two-step Msg1 1620 that may comprise arandom access preamble (RAP) transmission 1630 and one or more transportblocks transmission 1640, followed by a downlink (DL) transmission of atwo-step Msg2 1650 that may comprise a response, e.g., random accessresponse (RAR), corresponding to the uplink transmission. The responsemay comprise contention resolution information. For example, thetwo-step Msg1 1620 may be also referred to as a message A (MsgA). Forexample, the two-step Msg2 1650 may be also referred to as a message B(MsgB).

A base station may transmit one or more RRC messages to configure awireless device with one or more parameters of two step RACHconfiguration 1610. The one or more RRC messages may broadcast ormulticast to one or more wireless devices. The one or more RRC messagesmay be wireless device-specific messages, e.g., a dedicated RRC messagetransmitted to a wireless device with RRC INACTIVE 1520 or RRC CONNECTED1530. The one or more RRC messages may comprise parameters required fortransmitting a two-step Msg1 1620. For example, the parameter mayindicate at least one of following: PRACH resource allocation, preambleformat, SSB information (e.g., total number of SSBs, downlink resourceallocation of SSB transmission, transmission power of SSB transmission,and/or other information), and uplink radio resources for one or moretransport block transmissions.

In the UL transmission of a two-step RA procedure, a wireless device maytransmit, via a cell and to a base station, a RAP for UL time alignmentand/or one or more transport blocks (e.g., delay-sensitive data,wireless device ID, security information, device information such asIMSI, and/or other information). In the DL transmission of the two-stepRA procedure, a base station may transmit a two-step Msg2 1650 (e.g., anRAR) that may comprise at least one of following: a timing advancecommand indicating the TA value, a power control command, an UL grant(e.g., radio resource assignment, and/or MCS), a wireless device ID forcontention resolution, an RNTI (e.g., C-RNTI or TC-RNTI), and/or otherinformation. The two-step Msg2 1650 (e.g., an RAR) may comprise apreamble identifier corresponding to the preamble 1630, a positive ornegative acknowledgement of a reception of the one or more transportblocks 1640, and/or an indication of a successful decoding of the one ormore transport blocks 1640. A two-step RA procedure may reduce RAlatency compared with a four-step RA procedure, e.g., by integrating arandom access preamble transmission (e.g., a process to obtain a timingadvance value) with one or more transport block transmissions.

In the UL transmission of a two-step RA procedure, a wireless device maytransmit, via a cell and to a base station, an RAP in parallel with oneor more TBs. The wireless device may acquire one or more configurationparameters for the UL transmission before the wireless device starts atwo-step RA procedure, e.g., at step 1610 in FIG. 16. For example, theone or more configuration parameters may indicate at least one offollowing: PRACH resource allocation, preamble format, SSB information(e.g., a number of transmitting SSBs, downlink resource allocation ofSSB transmissions, transmission power of SSB transmission, and/or otherinformation), uplink radio resources (in terms of time, frequency,code/sequence/signature) for one or more transport block transmissions,and power control parameters of one or more TB transmissions (e.g., celland/or UE specific power adjustments used for calculating receivedtarget power, inter-cell interference control parameter that may be usedas a scaling factor of pathloss measurement, reference signal power tocalculate for pathloss measurement, and/or one or more margins).

There may be one or more ways for a wireless device to generate an RAP.For example, a two-step RACH configuration may comprise an RAPgenerating parameters (e.g., a root sequence) that may be employed bythe wireless device to generate an RAP. The wireless device may employthe RAP generating parameters to generate one or more candidatepreambles and may randomly select one of the candidate preambles as theRAP. The RAP generating parameters may be SSB specific and/orcell-specific. For example, a RAP generating parameters for a first SSBmay be different from or the same to a RAP generating parameters for asecond SSB. For example, a base station may transmit a control message(e.g., RRC message for a handover, and/or a PDCCH order for a secondarycell addition) that comprise a preamble index of an RAP dedicated to awireless device to initiate a two-step RA procedure. The one or morecandidate preambles may be organized into groups that may indicate anamount of data for transmission. In an example, the amount of data mayindicate one or more transport blocks that remain in the buffer. Each ofthe groups may be associated with a range of data size. For example, afirst group of the groups may comprise RAPs indicated for small datatransmissions, and a second group may comprise RAPs indicated for largerdata transmissions. A base station may transmit an RRC messagecomprising one or more thresholds with which a wireless device maydetermine a group of RAP by comparing the one or more thresholds and theamount of data. By transmitting an RAP from a specific group of RAPs,the wireless device may be able to indicate a size of data it may havefor transmission.

In a two-step RA procedure, a wireless device may transmit the RAP via aRACH resource indicated by a two-step RACH configuration. The wirelessdevice may transmit one or more TBs via an UL radio resource indicatedby a two-step RACH configuration. The transmission of the RAP may beoverlapped in time (partially or entirely) with the transmission of theone or more TBs. The two-step RACH configuration may indicate a portionof overlapping of radio resources between the RAP and one or more TBtransmissions. The two-step RACH configuration may indicate one or moreUL radio resources associated with one or more RAPs (or RAP groups)and/or the RACH resource. For example, based on a selection of an RAP,an RAP group, and/or an RACH resource, a wireless device may determineat least one UL radio resource where the wireless device transmits oneor more TBs as a part of a two-step RACH procedure. The one or more ULradio resources may be indicated based on a frame structure in FIG. 6,and/or OFDM radio structure in FIG. 8, e.g., with respect to an SFN(SNR=0), slot number, and/or OFDM symbol number for a time domain radioresource, and/or with respect to a subcarrier number, a number ofresource elements, a number of resource blocks, RBG number, and/orfrequency index for a frequency domain radio resource. For example, theone or more UL radio resources may be indicated based on a time offsetand/or a frequency offset with respect to one or more RACH resources ofa selected RAP. The UL transmissions may occur, e.g., in the samesubframe (or slot/mini-slot), in consecutive subframes (orslot/mini-slot), or in the same burst.

For example, a PRACH resource and one or more associated UL radioresources for a two-step Msg1 may be allocated with a time offset and/orfrequency offset, e.g., provided by RRC messages (as a part of RACHconfig.) and/or predefined (e.g., as a mapping table). FIG. 17A, FIG.17B, and FIG. 17C are examples of radio resource allocations of a PRACHresource and one or more associated UL radio resources based on a timeoffset, a frequency offset, and a combination of a time offset and afrequency offset, respectively. The examples in FIG. 17A, FIG. 17B, andFIG. 17C may be a case of a PRACH resource and a UL radio resource wherea single SSB transmission is configured. The examples may be a case of aPRACH resource and a UL radio resource associated with a first SSBtransmission of one or more SSB transmissions.

A base station may acquire a UL transmission timing by detecting an RAPtransmitted PRACH resource based on the time offset and/or the frequencyoffset. A base station may detect and/or decode one or more transportblocks transmitted via one or more associated UL radio resources basedon the UL transmission timing acquired from the RAP detection. Forexample, a base station may transmit one or more SSBs, and each of theone or more SSBs may have one or more associated PRACH and UL radioresources provided by a two-step RACH configuration. A wireless devicemay measure one or more SSBs, and based on measured received signalstrength (or based on other selection rule), may select at least oneSSB. The wireless device may respectively transmit an RAP and one ormore transport blocks via PRACH associated with the at least one SSB,and via UL radio resources associated with the PRACH and/or the at leastone SSB.

In an example, a base station may employ the RAP to adjust ULtransmission time for a cell and/or to aid in channel estimation for oneor more TBs. A portion of the UL transmission for one or more TBs in atwo-step RACH procedure may comprise, e.g., a wireless device ID, aC-RNTI, a service request such as buffer state reporting (e.g., a bufferstatus report) (BSR), one or more user data packets, and/or otherinformation. A wireless device in an RRC CONNECTED state may use aC-RNTI as an identifier of the wireless device (e.g., a wireless deviceID). A wireless device in an RRC INACTIVE state may use a C-RNTI (ifavailable), a resume ID, or a short MAC-ID as an identifier of thewireless device. A wireless device in an RRC IDLE state may use a C-RNTI(if available), a resume ID, a short MACID, an IMSI (InternationalMobile Subscriber Identifier), a T-IMSI (Temporary-IMSI), and/or arandom number as an identifier of the wireless device.

In a two-step RACH procedure, the UL transmission may comprise one ormore TBs that may be transmitted in one or more ways. One or moretransport blocks may be multiplexed with an RAP transmission in timeand/or frequency domains. A base station may configure one or moreresources reserved for the UL transmission that may be indicated to awireless device before the UL transmission. If a wireless devicetransmits one or more TBs in a two-step Msg1 1620 of a two-step RAprocedure, a base station may transmit in a two-step Msg2 1650 (e.g., anRAR) that may comprise a contention resolution message and/or anacknowledgement (ACK or NACK) message of the one or more TBs. A wirelessdevice may transmit one or more second TBs after the reception of anRAR. The wireless device may transmit an indicator, such as buffer statereporting, in a two-step Msg1 1620 of a two-step RA procedure. Theindicator may indicate to a base station an amount of data the wirelessdevice to transmit and/or an amount of data remains in a buffer. Thebase station may determine a UL grant based on the indicator. The basestation may transmit the UL grant to the wireless device via an RAR.

In a two-step/RA procedure, a wireless device may receive two separateresponses; a first response for RAP transmission; and a second responsefor one or more TB transmission. A wireless device may monitor a commonsearch space to detect the first response with a random access RNTIgenerated based on time and frequency indices of PRACH resource wherethe wireless device transmits an RAP. A wireless device may monitor acommon search space and/or a wireless device specific search space todetect the second response. To detect the second response, the wirelessdevice may employ a C-RNTI (e.g., if configured) or a random access RNTIgenerated based on time and frequency indices of PRACH resource wherethe wireless device transmits an RAP. The wireless device specificsearch space may be predefined and/or configured by an RRC message.

One or more events may trigger a two-step random access procedure. Forexample, one or more events may be at least one of following: initialaccess from RRC_IDLE, RRC connection re-establishment procedure,handover, DL or UL data arrival during RRC_CONNECTED when ULsynchronization status is non-synchronized, transition fromRRC_Inactive, beam failure recovery procedure, and/or request for othersystem information. For example, a PDCCH order, a MAC entity, and/or abeam failure indication may initiate a random access procedure.

A two-step RA procedure may be initiated based on one or more case-basedprocedures, services, or radio conditions. For example, a base stationin the cell may configure one or more wireless devices under itscoverage to use a two-step RA procedure, for example, if a cell is smallsuch that there may be no need for a TA. A wireless device may acquirethe configuration, via one or more RRC messages (e.g., MIB, systeminformation blocks, multicast and/or unicast RRC signaling), and/or viaL1 control signaling (e.g., PDCCH order) used to initiate a two-step RAprocedure.

For example, in a macro coverage area, a wireless device may have astored and/or persisted TA value, e.g., a stationary or near stationarywireless device such as a sensor-type wireless device. In this case atwo-step RA procedure may be initiated. A base station having macrocoverage may use broadcasting and/or dedicated signaling to configure atwo-step RA procedure with one or more wireless devices having storedand/or persisted TA value(s) under the coverage.

A wireless device in an RRC connected state may perform a two-step RAprocedure. For example, the two-step RA procedure may be initiated whena wireless device performs a handover (e.g., network-initiatedhandover), and/or when the wireless device requires or requests a ULgrant for a transmission of delay-sensitive data and there are nophysical-layer uplink control channel resources available to transmit ascheduling request. A wireless device in an RRC INACTIVE state mayperform a two-step RA procedure, e.g., for a small data transmissionwhile remaining in the RRC INACTIVE state or for resuming a connection.A wireless device may initiate a two-step RA procedure, for example, forinitial access such as establishing a radio link, re-establishment of aradio link, handover, establishment of UL synchronization, and/or ascheduling request when there is no UL grant.

The following description presents one or more examples of a RACHprocedure. The procedures and/or parameters described in the followingmay not be limited to a specific RA procedure. The procedures and/orparameters described in the following may be applied for a four-step RAprocedure and/or a two-step RA procedure. For example, a RA proceduremay refer to a four-step RA procedure and/or a two-step RA procedure inthe following description.

A wireless device may perform a cell search. For example, the wirelessdevice may acquire time and frequency synchronization with the cell anddetect a first physical layer cell ID of the cell during the cell searchprocedure. The wireless device may perform the cell search, for example,when the wireless device has received one or more synchronizationsignals (SS), for example, the primary synchronization signal (PSS) andthe secondary synchronization signal (SSS). The wireless device mayassume that reception occasions of one or more physical broadcastchannels (PBCH), PSS, and SSS are in consecutive symbols, and, forexample, form a SS/PBCH block (SSB). For example, the wireless devicemay assume that SSS, PBCH demodulation reference signal (DM-RS), andPBCH data have the same energy per resource element (EPRE). For example,the wireless device may assume that the ratio of PSS EPRE to SSS EPRE ina SS/PBCH block is a particular value (e.g., either 0 dB or 3 dB). Forexample, the wireless device may assume that the ratio of PDCCH DM-RSEPRE to SSS EPRE is within a particular range (e.g., from −8 dB to 8dB), for example, when the wireless device has not been provideddedicated higher layer parameters.

A wireless device may determine a first symbol index for one or morecandidate SS/PBCH block. For example, for a half frame with SS/PBCHblocks, the first symbol index for one or more candidate SS/PBCH blocksmay be determined according to a subcarrier spacing of the SS/PBCHblocks. For example, index 0 corresponds to the first symbol of thefirst slot in a half-frame. As an example, the first symbol of the oneor more candidate SS/PBCH blocks may have indexes {2, 8}+14·n for 15 kHzsubcarrier spacing, where, for example, n=0, 1 for carrier frequenciessmaller than or equal to 3 GHz, and for example, n=0, 1, 2, 3 forcarrier frequencies larger than 3 GHz and smaller than or equal to 6GHz. The one or more candidate SS/PBCH blocks in a half frame may beindexed in an ascending order in time, for example, from 0 to L−1. Thewireless device may determine some bits (for example, the 2 leastsignificant bits (LSB) for L=4, or the 3 LSB bits for L>4) of a SS/PBCHblock index per half frame from, for example, a one-to-one mapping withone or more index of a DM-RS sequence transmitted in the PBCH.

Prior to initiation of a random access procedure, a base station maytransmit one or more RRC messages to configure a wireless device withone or more parameters of RACH configuration. The one or more RRCmessages may broadcast or multicast to one or more wireless devices. Theone or more RRC messages may be wireless device-specific messages, e.g.,a dedicated RRC messages transmitted to a wireless device with RRCINACTIVE 1520 or RRC CONNECTED 1530. The one or more RRC messages maycomprise one or more parameters required for transmitting at least onepreamble via one or more random access resources. For example, the oneor more parameters may indicate at least one of the following: PRACHresource allocation, preamble format, SSB information (e.g., totalnumber of SSBs, downlink resource allocation of SSB transmission,transmission power of SSB transmission, SSB index corresponding to abeam transmitting the one or more RRC messages and/or otherinformation), and/or uplink radio resources for one or more transportblock transmissions.

The base station may further transmit one or more downlink referencesignals. For example, the one or more downlink reference signals maycomprise one or more discovery reference signals. The wireless devicemay select a first downlink reference signal among the one or moredownlink reference signals. For example, the first downlink referencesignal may comprise one or more synchronization signals and a physicalbroadcast channel (SS/PBCH). For example, the wireless device may adjusta downlink synchronization based on the one or more synchronizationsignals. For example, the one or more downlink reference signals maycomprise one or more channel state information-reference signals(CSI-RS).

The one or more RRC messages may further comprise one or more parametersindicating one or more downlink control channels, for example, PDCCH.Each of the one or more downlink control channels may be associated withat least one of the one or more downlink reference signals. For example,the first downlink reference signal may comprise one or more systeminformation (e.g., master information block (MIB) and/or systeminformation block (SIB)). The base station may transmit the one or moresystem information, for example, on the physical broadcast channel(PBCH), physical downlink control channel (PDCCH), and/or physicaldownlink shared channel (PDSCH).

The one or more system information may comprise at least one informationelement (e.g., PDCCH-Config, PDCCH-ConfigSIB1, PDCCH-ConfigCommon). Theat least one information element may be used, for example, to configurea wireless device with one or more control parameters. The one or morecontrol parameters may comprise one or more parameters of one or morecontrol resource sets (CORESET). For example, the one or more controlparameters may comprise the parameters of a first common CORESET #0(e.g., controlResourceSetZero), and/or a second common CORESET (e.g.,commonControlResourceSet). The one or more control parameters mayfurther comprise one or more search space sets. For example, the one ormore control parameters may comprise the parameters of a first searchspace for the system information block (e.g., searchSpaceSIB1), and/or afirst common search space #0 (e.g., searchSpaceZero), and/or a firstrandom access search space (e.g., ra-SearchSpace), and/or a first pagingsearch space (e.g., pagingSearchSpace). For example, the wireless devicemay use the one or more control parameters to acquire the one or moredownlink control channels.

For example, a wireless device may monitor a set of one or morecandidates for the one or more downlink control channels in the one ormore control resource sets. The one or more control resource sets may beon a first active downlink frequency band, e.g., an active bandwidthpart (BWP), on a first activated serving cell. For example, the firstactivated serving cell may be configured with the one or more controlparameters according to the one or more search space sets. For example,the wireless device may decode each of the one or more downlink controlchannels in the set of candidates for the one or more downlink controlchannels according to a first format of a first downlink controlinformation (DCI). For example, the set of candidates for the one ormore downlink control channels may be defined in terms of the one ormore search space sets. For example, the one or more search space setsmay be one or more common search space sets (e.g., Type0-PDCCH,Type0A-PDCCH, Type1-PDCCH, Type2-PDCCH, and/or Type3-PDCCH), and/or oneor more wireless device-specific search space sets.

For example, the wireless device may monitor the set of candidates forthe one or more downlink control channels in a Type0-PDCCH common searchspace set. For example, the Type0-PDCCH common search space set may beconfigured by the at least one information element, e.g., thePDCCH-ConfigSIB1 in the MIB. For example, the Type0-PDCCH common searchspace set may be configured by the one or more search space sets, e.g.,a searchSpaceSIB1 in the PDCCH-ConfigCommon, or the searchSpaceZero inthe PDCCH-ConfigCommon. For example, the Type0-PDCCH common search spaceset may be configured for a first format of a first downlink controlinformation scrambled by a first radio network temporary identifier,e.g., a system information-radio network temporary identifier (SI-RNTI).

For example, the wireless device may monitor the set of candidates forthe one or more downlink control channels in a Type1-PDCCH common searchspace set. For example, the Type1-PDCCH common search space set may beconfigured by the one or more search space sets, e.g., thera-searchSpace in the PDCCH-ConfigCommon. For example, the Type1-PDCCHcommon search space set may be configured for a second format of asecond downlink control information scrambled by a second radio networktemporary identifier, e.g., a random access-radio network temporaryidentifier (RA-RNTI), or a temporary cell-radio network temporaryidentifier (TC-RNTI).

The wireless device may determine, for example during a cell search,that a first control resource set for a first common search space (e.g.,Type0-PDCCH) is present. The first control resource set may comprise oneor more resource blocks and one or more symbols. The one or more RRCmessages may comprise one or more parameters indicating one or moremonitoring occasions of the one or more downlink control channels. Forexample, the wireless device may determine a number of consecutiveresource blocks and a number of consecutive symbols for the firstcontrol resource set of the first common search space. For example, oneor more bits (e.g., a four most significant bits) of the at least oneinformation element (e.g., PDCCH-ConfigSIB1) may indicate the number ofconsecutive resource blocks and the number of consecutive symbols. Forexample, the wireless device may determine the one or more monitoringoccasions of the one or more downlink control channels from one or morebits (e.g., a four least significant bits) of the at least oneinformation element (e.g., PDCCH-ConfigSIB1). For example, the one ormore monitoring occasions of the one or more downlink control channelsassociated with the first downlink reference signal may be determinedbased on one or more system frame numbers and one or more slot indexesof the first control resource set. For example, the first downlinkreference signal with a first index may overlap in time with the firstframe number and the first slot index.

The wireless device may determine a first downlink channel among the oneor more downlink control channels, based on the first downlink referencesignal. For example, the first downlink channel may be a first downlinkcontrol channel, or a first system information block (e.g., SIB1). Thewireless device may assume that a demodulation reference signal antennaport associated with a reception of the first downlink channel is quasico-located (QCL) with the first downlink reference signal. For example,the demodulation reference signal antenna port associated with thereception of the first downlink channel and the first downlink referencesignal (e.g., the corresponding SS/PBCH block) may be quasi co-locatedwith respect to at least one of the following: an average gain,QCL-TypeA, and/or QCL-TypeD.

A physical layer of the wireless device may receive, from higher layers,one or more SS/PBCH block indexes. For example, the physical layer mayreceive one or more configuration parameters of one or more physicalrandom access channel (PRACH) transmission parameters (e.g., the one ormore PRACH transmission parameters may indicate PRACH preamble format,preamble index, a corresponding RA-RNTI, time resources, and/orfrequency resources for PRACH transmission), and/or parameters fordetermining one or more sequences and their shifts in the PRACH preamblesequence set (e.g., set type). The physical layer may provide to higherlayers one or more corresponding sets of reference signal received power(RSRP) measurements.

The random access procedure may comprise one or more transmissions of arandom access preamble (e.g., Msg1) in one or more PRACH occasions. Therandom access procedure may further comprise one or more transmissionsof one or more random access response (RAR) messages, for example, withone or more physical downlink channels (e.g., Msg2). The random accessprocedure may further comprise one or more Msg3 in one or more physicaluplink channels (e.g., PUSCH), and one or more physical downlinkchannels (PDSCH) for contention resolution. The random access proceduremay be triggered upon request of one or more PRACH transmissions, forexample, by higher layers or by one or more control orders (e.g., PDCCHorder).

A MAC entity of the wireless device may select one or more random accessresources for a random access procedure initiated. The MAC entity mayselect a first downlink reference signal. For example, the MAC entitymay select the first downlink reference signal (e.g., a first SS/PBCHblock (SSB), or a first channel state information-reference signal(CSI-RS)) with the first reference signal received power (RSRP) above afirst reference signal received power threshold. For example, the firstreference signal received power threshold may be defined per a type ofreference signal (e.g., rsrp-ThresholdSSB may for a SSB, andrsrp-ThresholdCSI-RS for a CSI-RS). The first reference signal receivedpower threshold may be broadcast, semi-statically configured, and/orpredefined. For example, the MAC entity may select the first downlinkreference signal for contention-free random access procedure, forexample for beam failure recovery, or system information request. Forexample, the MAC entity may select the first downlink reference signalfor contention-based random access procedure.

The wireless device may select one or more random access resources. Theone or more random access resources may, for example, comprise one ormore random access preambles, one or more time resources, and/or one ormore frequency resources for PRACH transmission. The one or more randomaccess resources may be predefined. The one or more random accessresources may be provided by one or more RRC messages. The one or morerandom access resources may be provided by one or more downlink controlorders (e.g., PDCCH order). The one or more random access resources maybe determined based on the first downlink reference signal. For example,the wireless device may set a first preamble index to a parameter (e.g.,ra-PreambleIndex) corresponding to the first downlink reference signal.

The wireless device may transmit at least one random access preamble inthe one or more random access resources. For example, the wirelessdevice may transmit a first preamble with the first preamble index. Thefirst preamble may be transmitted using a first PRACH format with afirst transmission power on one or more PRACH resources. The one or morePRACH resources may comprise one or more PRACH occasions.

The one or more RRC messages may comprise one or more random accessparameters. For example, a cell specific random access configurationmessage (e.g., RACH-ConfigCommon and/or RACH-ConfigGeneric) may compriseat least one of the following: a total number of random access preambles(e.g., totalNumberOfRA-Preambles), one or more PRACH configuration index(e.g., prach-ConfigurationIndex), a number of PRACH occasions that maybe multiplexed in frequency domain (FDMed) in a time instance (e.g.,msg1-FDM), an offset of a lowest PRACH occasion in frequency domain withrespect to a first resource block (e.g., msg1-FrequencyStart), a powerramping step for PRACH (e.g., powerRampingStep), a target power level atthe network receiver side (preambleReceivedTargetPower), a maximumnumber of random access preamble transmission that may be performed(e.g., preambleTransMax), a window length for a random access response(i.e., RAR, e.g., Msg2) (e.g., ra-ResponseWindow), a number of SSBs perrandom access channel (RACH) occasion and a number of contention-basedpreambles per SSB (e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB). Forexample, the total number of random access preambles may be a multipleof the number of SSBs per RACH occasion. For example, the window lengthfor RAR may be in number of slots. For example, a dedicated randomaccess configuration message (e.g., RACH-ConfigDedicated) may compriseone or more RACH occasions for contention-free random access (e.g.,occasions), and one or more PRACH mask index for random access resourceselection (e.g., ra-ssb-OccasionMaskIndex).

The one or more random access parameters (e.g.,ssb-perRACH-OccasionAndCB-PreamblesPerSSB) may provide the wirelessdevice with a first number (e.g., N) of the one or more downlinkreference signals (e.g., SS/PBCH blocks) that may be associated with afirst PRACH occasion. The one or more random access parameters (e.g.,ssb-perRACH-OccasionAndCB-PreamblesPerSSB) may provide the wirelessdevice with a second number (e.g., R) of the one or more random accesspreambles for the first downlink reference signal and for the firstPRACH occasion. The one or more random access preambles may becontention based preambles. The first downlink reference signal may be afirst SS/PBCH block. For example, according to the first number (e.g.,if N<1), the first SS/PBCH block may be mapped to at least one (e.g.,1/N) consecutive valid PRACH occasions. For example, according to thesecond number (e.g., R), at least one preamble with consecutive indexesassociated with the first SS/PBCH block may start from the firstpreamble index for the first valid PRACH occasion.

For example, the one or more PRACH configuration indexes (e.g.,prach-ConfigurationIndex), may indicate a preamble format, a periodicityfor the one or more PRACH time resources, one or more PRACH subframenumbers, a number of PRACH slots within the one or more PRACH subframes,a PRACH starting symbol number, and/or a number of time domain PRACHoccasions within the first PRACH slot.

The one or more random access parameters may further comprise anassociation period for mapping the one or more SS/PBCH blocks to the oneor more PRACH occasions. For example, the one or more SS/PBCH blockindexes may be mapped to the one or more PRACH occasions based on anorder. For example, the order may be as follows: In increasing order ofthe indexes of the at least one preamble in the first PRACH occasion. Inincreasing order of the indexes of the one or more frequency resources(e.g., for frequency multiplexed PRACH occasions). In increasing orderof the indexes of the one or more time resources (e.g., for timemultiplexed PRACH occasions) in the first PRACH slot. In increasingorder of the indexes for the PRACH slots.

For example, for the PRACH transmission triggered by the one or morecontrol orders (e.g., PDCCH order), one or more PRACH mask indexes(e.g., ra-ssb-OccasionMaskIndex) may indicate the one or more PRACHoccasions. The one or more PRACH occasions may be associated with thefirst SS/PBCH block index indicated by the one or more control orders.For example, the PRACH occasions may be mapped consecutively for thefirst SS/PBCH block index. The wireless device may select the firstPRACH occasion indicated by a first PRACH mask index value for the firstSS/PBCH block index in the first association period. The firstassociation period may be a first mapping cycle. The wireless device mayreset the one or more indexes of the one or more PRACH occasions for thefirst mapping cycle.

In an example, a base station may transmit, to a wireless device, one ormore messages indicating random access parameters of a four-step randomaccess procedure in FIG. 12 and/or a two-step random access procedure inFIG. 16. For example, the one or more messages may be broadcast RRCmessage, wireless device specific RRC message, and/or combinationthereof. For example, the one or more message may comprise at least oneof random access common configuration (e.g., RACH-ConfigCommon), randomaccess generic configuration (e.g., RACH-ConfigGeneric), and/or randomaccess configuration dedicated to a wireless device (e.g.,RACH-ConfigDedicated). For example, for a contention based (four-stepand/or a two-step) random access procedure, a wireless device mayreceive, from a base station, at least RACH-ConfigCommon andRACH-ConfigGeneric. For example, for a contention free (four-step and/ora two-step) random access procedure, a wireless device may receive, froma base station, at least RACH-ConfigDedicated.

For example, a random access procedure may be initiated in one or moreways at least based on one of RACH-ConfigCommon, RACH-ConfigGeneric, andRACH-ConfigDedicated. For example, a random access procedure may beinitiated by a PDCCH order transmitted by a base station, by the MACentity of a wireless device, and/or by RRC. There may be one randomaccess procedure ongoing at any point in time in a MAC entity. A randomaccess procedure on an SCell may be initiated by a PDCCH order withra-PreambleIndex different from a first index (that may be predefined orconfigured e.g., 0b000000). For example, if the MAC entity of a wirelessdevice receives a request for a random access procedure while another isalready ongoing in the MAC entity, a wireless device may continue withthe ongoing procedure or start with the new procedure (e.g. for SIrequest).

An example random access common configuration (e.g., RACH-ConfigCommon)may be below:

RACH-ConfigCommon ::= SEQUENCE { rach-ConfigGeneric RACH-ConfigGeneric,totalNumberOfRA-Preambles INTEGER (1..63) OPTIONAL, -- Need Sssb-perRACH-OccasionAndCB-PreamblesPerSSB CHOICE { oneEighth ENUMERATED{n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64},oneFourth ENUMERATED{n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64}, oneHalfENUMERATED{n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64}, oneENUMERATEDn4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64}, twoENUMERATED {n4,n8,n12,n16,n20,n24,n28,n32}, four INTEGER (1..16), eightINTEGER (1..8), sixteen INTEGER (1..4) } OPTIONAL,-- Need MgroupBconfigured SEQUENCE { ra-Msg3SizeGroupA ENUMERATED { b56, b144,b208, b256, b282, b480, b640, b800, b1000, spare7, spare6, spare5,spare4, spare3, spare2, spare1}, messagePowerOffsetGroupB ENUMERATED {minusinfinity, dB0, dB5, dB8, dB10, dB12, dB15, dB18},numberOfRA-PreamblesGroupA INTEGER (1..64) } OPTIONAL,-- Need Rra-ContentionResolutionTimer ENUMERATED { sf8, sf16, sf24, sf32, sf40,sf48, sf56, sf64}, rsrp-ThresholdSSB RSRP-Range OPTIONAL, -- Need Rrsrp-ThresholdSSB-SUL RSRP-Range OPTIONAL, -- Cond SULprach-RootSequenceIndex CHOICE { l839 INTEGER (0..837), l139 INTEGER(0..137) }, msg1-SubcarrierSpacing SubcarrierSpacing OPTIONAL, --Need SrestrictedSetConfig ENUMERATED {unrestrictedSet, restrictedSetTypeA,restrictedSetTypeB}, msg3-transformPrecoding ENUMERATED{enabled} OPTIONAL, -- Need R ... }

For example, messagePowerOffsetGroupB may indicate a threshold forpreamble selection. The value of messagePowerOffsetGroupB may be in dB.For example, minusinfinity in RACH-ConfigCommon may corresponds to−infinity. The value dB0 may correspond to 0 dB, dB5 may correspond to 5dB and so on. msg1-SubcarrierSpacing in RACH-ConfigCommon may indicate asubcarrier spacing of PRACH. One or more values, e.g., 15 or 30 kHz (<6GHz), 60 or 120 kHz (>6 GHz) may be applicable. There may be a layer 1parameter (e.g., ‘prach-Msg1SubcarrierSpacing) corresponding tomsg1-SubcarrierSpacing. A wireless device may apply the SCS as derivedfrom the prach-ConfigurationIndex in RACH-ConfigGeneric, for example, ifthis parameter is absent. A base station may employmsg3-transformPrecoding to indicate to a wireless device whethertransform precoding is enabled for data transmission (e.g., Msg3 in afour-step RA procedure and/or one or more TB transmission in a two-stepRA procedure). Absence of msg3-transformPrecoding may indicate that itis disabled. numberOfRA-PreamblesGroupA may indicate a number ofcontention based (CB) preambles per SSB in group A. This may determineimplicitly the number of CB preambles per SSB available in group B. Thesetting may be consistent with the setting ofssb-perRACH-OccasionAndCB-PreamblesPerSSB. prach-RootSequenceIndex mayindicate PRACH root sequence index. There may be a layer 1 parameter(e.g., ‘PRACHRootSequenceIndex’) corresponding tossb-perRACH-OccasionAndCB-PreamblePerSSB. The value range may depend ona size of preamble, e.g., whether a preamble length (L) is L=839 orL=139. ra-ContentionResolutionTimer may indicate an initial value forthe contention resolution timer. For example, a value ms8 inRACH-ConfigCommon may indicate 8 ms, value ms16 may indicate 16 ms, andso on. ra-Msg3SizeGroupA may indicate a transport blocks size thresholdin bit. For example, a wireless device may employ a contention based RApreamble of group A, for example, when the transport block size is belowra-Msg3SizeGroupA. rach-ConfigGeneric may indicate one or more genericRACH parameters in RACH-ConfigGeneric. restrictedSetConfig may indicatea configuration of an unrestricted set or one of two types of restrictedsets. rsrp-ThresholdSSB may indicate a threshold for SS block selection.For example, a wireless device may select the SS block and correspondingPRACH resource for path-loss estimation and (re)transmission based on SSblocks that satisfy the threshold. rsrp-ThresholdSSB-SUL may indicate athreshold for uplink carrier selection. For example, a wireless devicemay select an SUL carrier to perform random access based on thisthreshold. ssb-perRACH-OccasionAndCB-PreamblesPerSSB may indicate anumber of SSBs per RACH occasion and a number of contention basedpreambles per SSB. There may be layer 1 one or more parameters (e.g.,‘SSB-per-rach-occasion’ and/or ‘CB-preambles-per-SSB’) corresponding tossb-perRACH-OccasionAndCB-PreamblesPerSSB. For example, a total numberof CB preambles in a RACH occasion may be given byCB-preambles-per-SSB*max(1,SSB-per-rach-occasion).totalNumberOfRA-Preambles may indicate a total number of preamblesemployed for contention based and contention free random access. Forexample, totalNumberOfRA-Preambles may not comprise one or morepreambles employed for other purposes (e.g. for SI request). A wirelessdevice may use one or more of 64 preambles for RA, for example, if thefield is absent.

An example random access common configuration of RACH-ConfigGeneric maybe below:

RACH-ConfigGeneric ::= SEQUENCE { prach-ConfigurationIndex INTEGER(0..255), msg1-FDM ENUMERATED {one, two, four, eight},msg1-FrequencyStart INTEGER (0..maxNrofPhysicalResourceBlocks-1),zeroCorrelationZoneConfig INTEGER(0..15), preambleReceivedTargetPowerINTEGER (−202..−60), preambleTransMax ENUMERATED {n3, n4, n5, n6, n7,n8,n10, n20, n50, n100, n200), powerRampingStep ENUMERATED {dB0, dB2, dB4,dB6}, ra-ResponseWindow ENUMERATED {sl1, sl2, sl4, sl8, sl10, sl20,sl40, sl80}, ... }

For example, msg1-FDM may indicate a number of PRACH transmissionoccasions FDMed in one time instance. There may be a layer 1 parameter(e.g., ‘prach-FDM’) corresponding to msg1-FDM. msg1-FrequencyStart mayindicate an offset of PRACH transmission occasion (e.g., lowest PRACHtransmission occasion) in frequency domain with respective to aparticular PRB (e.g., PRB 0). A base station may configure a value ofmsg1-FrequencyStart such that the corresponding RACH resource is withinthe bandwidth of the UL BWP. There may be a layer 1 parameter (e.g.,‘prach-frequency-start’) corresponding to msg1-FreqencyStart.powerRampingStep may indicate power ramping steps for PRACH.prach-ConfigurationIndex may indicate a PRACH configuration index. Forexample, a radio access technology (e.g., LTE, and/or NR) may predefineone or more PRACH configurations, and prach-ConfigurationIndex mayindicate one of the one or more PRACH configurations. There may be alayer 1 parameter (e.g., ‘PRACHConfigurationIndex’) corresponding toprach-ConfigurationIndex. preambleReceivedTargetPower may indicate atarget power level at the network receiver side. For example, multiplesof a particular value (e.g., in dBm) may be chosen. RACH-ConfigGenericabove shows an example when multiples of 2 dBm are chosen (e.g. −202,−200, −198, . . . ). preambleTransMax may indicate a number of RApreamble transmissions performed before declaring a failure. Forexample, preambleTransMax may indicate a maximum number of RA preambletransmissions performed before declaring a failure. ra-ResponseWindowmay indicate an RAR window length in number of slots (or subframes,mini-slots, and/or symbols). a base station may configure a value lowerthan or equal to a particular value (e.g., 10 ms). The value may belarger than a particular value (e.g., 10 ms). zeroCorrelationZoneConfigmay indicate an index of preamble sequence generation configuration(e.g., N-CS configuration). A radio access technology (e.g., LTE and/orNR) may predefine one or more preamble sequence generationconfigurations, and zeroCorrelationZoneConfig may indicate one of theone or more preamble sequence generation configurations. For example, awireless device may determine a cyclic shift of preamble sequence basedon zeroCorrelationZoneConfig. zeroCorrelationZoneConfig may determine aproperty of random access preambles (e.g., a zero correlation zone)

An example random access dedicated configuration (e.g.,RACH-ConfigDedicated) may be below:

RACH-ConfigDedicated ::= SEQUENCE { cfra CFRA OPTIONAL, -- Need Nra-Prioritization RA-Prioritization OPTIONAL, -- Need N ... } CFRA ::=SEQUENCE { occasions SEQUENCE { rach-ConfigGeneric RACH-ConfigGeneric,ssb-perRACH-Occasion ENUMERATED {oneEighth, oneFourth, oneHalf, one,two, four, eight, sixteen} OPTIONAL -- Cond SSB-CFRA } OPTIONAL,-- NeedS resources CHOICE { ssb  SEQUENCE {  ssb-ResourceList SEQUENCE(SIZE(1..maxRA-SSB-Resources)) OF CFRA-SSB-Resource, ra-ssb-OccasionMaskIndex INTEGER (0..15) }, csirs SEQUENCE { csirs-ResourceList SEQUENCE (SIZE(1..maxRA-CSIRS-Resources)) OFCFRA-CSIRS-Resource,  rsrp-ThresholdCSI-RS RSRP-Range } }, ... }CFRA-SSB-Resource ::= SEQUENCE { ssb SSB-Index, ra-PreambleIndex INTEGER(0..63), ... } CFRA-CSIRS-Resource ::= SEQUENCE { csi-RS CSI-RS-Index,ra-OccasionList SEQUENCE (SIZE(1..maxRA-OccasionsPerCSIRS)) OF INTEGER(0..maxRA-Occasions-1), ra-PreambleIndex INTEGER (0..63), ... }

For example, csi-RS may indicate an identifier (e.g., ID) of a CSI-RSresource defined in the measurement object associated with this servingcell. ra-OccasionList may indicate one or more RA occasions. A wirelessdevice may employ the one or more RA occasions, for example, when thewireless device performs a contention-free random access (CFRA)procedure upon selecting the candidate beam identified by this CSI-RS.ra-PreambleIndex may indicate an RA preamble index to use in the RAoccasions associated with this CSI-RS. ra-ssb-OccasionMaskIndex mayindicate a PRACH Mask Index for RA Resource selection. The mask may bevalid for one or more SSB resources signaled in ssb-ResourceList.rach-ConfigGeneric may indicate a configuration of contention freerandom access occasions for the CFRA procedure. ssb-perRACH-Occasion mayindicate a number of SSBs per RACH occasion. ra-PreambleIndex mayindicate a preamble index that a wireless device may employ whenperforming CF-RA upon selecting the candidate beams identified by thisSSB. ssb in RACH-ConfigDedicated may indicate an identifier (e.g., ID)of an SSB transmitted by this serving cell. cfra in RACH-ConfigDedicatedmay indicate one or more parameters for contention free random access toa given target cell. A wireless device may perform contention basedrandom access, for example, if the field (e.g., cfra) is absent.ra-prioritization may indicate one or more parameters which apply forprioritized random access procedure to a given target cell. A field,SSB-CFRA, in RACH-ConfigDedicated may be present, for example, if thefield resources in CFRA is set to ssb; otherwise it may be not present.

In an example, a base station may transmit, to a wireless device, one ormore RRC message indicating at least one of following for a randomaccess procedure:

an available set of PRACH occasions for the transmission of the RandomAccess Preamble (e.g., prach-ConfigIndex), an initial Random AccessPreamble power (e.g., preambleReceivedTargetPower), an RSRP thresholdfor the selection of the SSB and corresponding Random Access Preambleand/or PRACH occasion (e.g., rsrp-ThresholdSSB, rsrp-ThresholdSSB may beconfigured in a beam failure recovery configuration, e.g.,BeamFailureRecoveryConfig IE, for example, if the Random Accessprocedure is initiated for beam failure recovery), an RSRP threshold forthe selection of CSI-RS and corresponding Random Access Preamble and/orPRACH occasion (e.g., rsrp-ThresholdCSI-RS, rsrp-ThresholdCSI-RS may beset to a value calculated based on rsrp-ThresholdSSB and an offsetvalue, e.g., by multiplying rsrp-ThresholdSSB by powerControlOffset), anRSRP threshold for the selection between the NUL carrier and the SULcarrier (e.g., rsrp-ThresholdSSB-SUL), a power offset betweenrsrp-ThresholdSSB and rsrp-ThresholdCSI-RS to be employed when theRandom Access procedure is initiated for beam failure recovery (e.g.,powerControlOffset), a power-ramping factor (e.g., powerRampingStep), apower-ramping factor in case of differentiated Random Access procedure(e.g., powerRampingStepHighPriority), an index of Random Access Preamble(e.g., ra-PreambleIndex), an index (e.g., ra-ssb-OccasionMaskIndex)indicating PRACH occasion(s) associated with an SSB in which the MACentity may transmit a Random Access Preamble (e.g., FIG. 18 shows anexample of ra-ssb-OccasionMaskIndex values), PRACH occasion(s)associated with a CSI-RS in which the MAC entity may transmit a RandomAccess Preamble (e.g., ra-OccasionList), a maximum number of RandomAccess Preamble transmission (e.g., preambleTransMax), a number of SSBsmapped to each PRACH occasion and a number of Random Access Preamblesmapped to each SSB (e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB, thetime window (duration, and/or interval) to monitor RA response(s) (e.g.,ra-ResponseWindow) and/or a Contention Resolution Timer (e.g.,ra-ContentionResolutionTimer).

In an example, a random access procedure may be initiated for beamfailure detection and recovery. For example, a wireless device may beconfigured by RRC with a beam failure recovery procedure which may beemployed for indicating to the serving base station of a SSB or CSI-RSwhen beam failure is detected on the serving SSB(s)/CSI-RS(s). Beamfailure may be detected by counting one or more beam failure instanceindication from the lower layers to the MAC entity. For example, a basestation may configure a wireless device by transmitting an RRC message(e.g., comprising a beam failure recovery configuration, e.g.,BeamFailureRecoveryConfig) indicating at least one of following:beamFailureInstanceMaxCount for the beam failure detection.beamFailureDetectionTimer for the beam failure detection,beamFailureRecoveryTimer for the beam failure recovery procedure,rsrp-ThresholdSSB for an RSRP threshold for the beam failure recovery,powerRampingStep for the beam failure recovery,preambleReceivedTargetPower, preambleReceivedTargetPower for the beamfailure recovery, preambleTransMax for the beam failure recovery, thetime window (e.g., ra-ResponseWindow) to monitor response(s) for thebeam failure recovery using contention-free Random Access Preamble,prach-ConfigIndex for the beam failure recovery,ra-ssb-OccasionMaskIndex for the beam failure recovery, ra-OccasionListfor the beam failure recovery.

In an example, a wireless device may employ one or more parameters for arandom access procedure. For example, a wireless device may employ atleast one of PREAMBLE_INDEX; PREAMBLE_TRANSMISSION_COUNTER;PREAMBLE_POWER_RAMPING_COUNTER; PREAMBLE_POWER_RAMPING_STEP;PREAMBLE_RECEIVED_TARGET_POWER; PREAMBLE_BACKOFF; PCMAX;SCALING_FACTOR_BI; and TEMPORARY_C-RNTI.

In an example, a wireless device may perform random access resourceselection for selecting one or more preambles and one or more PRACHoccasion (or resources comprising time, frequency, and/or code). Forexample, there may be one or more cases that a random access proceduremay be initiated for beam failure recovery; and/or thebeamFailureRecoveryTimer is either running or not configured; and/or thecontention-free Random Access Resources for beam failure recoveryrequest associated with any of the SSBs and/or CSI-RSs have beenexplicitly provided by RRC; and/or at least one of the SSBs with SS-RSRPabove rsrp-ThresholdSSB amongst the SSBs in candidateBeamRSList or theCSI-RSs with CSI-RSRP above rsrp-ThresholdCSI-RS amongst the CSI-RSs incandidateBeamRSList is available. In this case, a wireless device mayselect one or more SSBs with corresponding one or more SS-RSRP valuesabove rsrp-ThresholdSSB amongst the SSBs in candidateBeamRSList or oneor more CSI-RSs with corresponding one or more CSI-RSRP values aboversrp-ThresholdCSI-RS amongst the CSI-RSs in candidateBeamRSList. Forexample, a wireless device may select at least one CSI-RS and set thePREAMBLE_INDEX to a ra-PreambleIndex corresponding to the SSB incandidateBeamRSList which is quasi-collocated with the at least oneCSI-RS selected by the wireless device, for example, if there is nora-PreambleIndex associated with the at least one CSI-RS, otherwise thewireless device may set the PREAMBLE_INDEX to a ra-PreambleIndexcorresponding to the selected SSB or CSI-RS from the set of RandomAccess Preambles for beam failure recovery request.

For example, a wireless device may be under one of following cases: arandom access procedure may be initiated, a ra-PreambleIndex has beenprovided by either PDCCH or RRC, the ra-PreambleIndex is not a firstpreamble index (that may be predefined or configured e.g., 0b000000),contention-free Random Access Resource associated with SSBs or CSI-RSshave not been provided by RRC. In this case, the wireless device may setthe PREAMBLE_INDEX to the signaled ra-PreambleIndex.

For example, there may be one or more cases that a random accessprocedure may be initiated and/or the contention-free Random AccessResources associated with SSBs have been explicitly provided by RRC andat least one SSB with SS-RSRP above rsrp-ThresholdSSB amongst theassociated SSBs is available. In this case, a wireless device may selectan SSB with SS-RSRP above rsrp-ThresholdSSB amongst the associated SSBs.For example, the wireless device may set the PREAMBLE_INDEX to ara-PreambleIndex corresponding to the selected SSB.

For example, there may be one or more cases that a random accessprocedure may be initiated, and the contention-free random accessresources associated with CSI-RSs have been explicitly provided by RRCand at least one CSI-RS with CSI-RSRP above rsrp-ThresholdCSI-RS amongstthe associated CSI-RSs is available. In this case, a wireless device mayselect a CSI-RS with CSI-RSRP above rsrp-ThresholdCSI-RS amongst theassociated CSI-RSs. for example, the wireless device may set thePREAMBLE_INDEX to a ra-PreambleIndex corresponding to the selectedCSI-RS.

For example, there may be one or more cases that a random accessprocedure may be initiated and at least one of the SSBs with SS-RSRPabove rsrp-ThresholdSSB is available. In this case, for example, awireless device may select an SSB with SS-RSRP above rsrp-ThresholdSSB,otherwise may select any SSB. For example, a random access resourceselection is performed when Msg3 1240, two-step Msg1 1620, and/or one ormore TBs 1640 is being retransmitted, a wireless device may select thesame group of Random Access Preambles as was employed for the RandomAccess Preamble transmission attempt corresponding to the firsttransmission of Msg3, two-step Msg1 1620, and/or one or more TBs 1640.For example, if the association between random access preambles and SSBsis configured, a wireless device may select a ra-PreambleIndex randomlywith equal probability from the Random Access Preambles associated withthe selected SSB and the selected Random Access Preambles group. Forexample, if the association between random access preambles and SSBs isnot configured, a wireless device may select a ra-PreambleIndex randomlywith equal probability from the Random Access Preambles within theselected Random Access Preambles group. For example, a wireless devicemay set the PREAMBLE_INDEX to the selected ra-PreambleIndex.

In an example, if an SSB is selected above and an association betweenPRACH occasions and SSBs is configured, a wireless device may determinethe next available PRACH occasion from the PRACH occasions correspondingto the selected SSB permitted by the restrictions given by thera-ssb-OccasionMaskIndex if configured (the MAC entity of the wirelessdevice may select a PRACH occasion randomly with equal probabilityamongst the PRACH occasions occurring simultaneously but on differentsubcarriers, corresponding to the selected SSB; the MAC entity may takeinto account the possible occurrence of measurement gaps whendetermining the next available PRACH occasion corresponding to theselected SSB).

In an example, if a CSI-RS is selected above and an association betweenPRACH occasions and CSI-RSs is configured. a wireless device maydetermine the next available PRACH occasion from the PRACH occasions inra-OccasionList corresponding to the selected CSI-RS (the MAC entityshall select a PRACH occasion randomly with equal probability amongstthe PRACH occasions occurring simultaneously but on differentsubcarriers, corresponding to the selected CSI-RS; the MAC entity maytake into account the possible occurrence of measurement gaps whendetermining the next available PRACH occasion corresponding to theselected CSI-RS).

In an example, if a CSI-RS is selected above and there is nocontention-free Random Access Resource associated with the selectedCSI-RS, a wireless device may determine the next available PRACHoccasion from the PRACH occasions, permitted by the restrictions givenby the ra-ssb-OccasionMaskIndex if configured, corresponding to the SSBin candidateBeamRSList which is quasi-collocated with the selectedCSI-RS (the MAC entity may take into account the possible occurrence ofmeasurement gaps when determining the next available PRACH occasioncorresponding to the SSB which is quasi-collocated with the selectedCSI-RS).

For example, a wireless device may determine the next available PRACHoccasion (the MAC entity shall select a PRACH occasion randomly withequal probability amongst the PRACH occasions occurring simultaneouslybut on different subcarriers; the MAC entity may take into account thepossible occurrence of measurement gaps when determining the nextavailable PRACH occasion).

For example, based on a selected PREAMBLE INDEX and PRACH occasion, awireless device may perform the random access preamble transmission. Forexample, if the notification of suspending power ramping counter has notbeen received from lower layers; and/or if SSB selected is not changed(i.e. same as the previous Random Access Preamble transmission), awireless device may increment PREAMBLE_POWER_RAMPING_COUNTER by 1. thewireless device may select a value of DELTA_PREAMBLE that may bepredefined and/or semi-statically configured by a base station and setPREAMBLE_RECEIVED_TARGET_POWER topreambleReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_POWER_RAMPING_COUNTER−1)×PREAMBLE_POWER_RAMPING_STEP.

The wireless device may instruct the physical layer to transmit theRandom Access Preamble using the selected PRACH, corresponding RA-RNTI(e.g., if available), PREAMBLE_INDEX and PREAMBLE_RECEIVED_TARGET_POWER.For example, the wireless device may compute an RA-RNTI associated withthe PRACH occasion in which the Random Access Preamble is transmitted,e.g., In an example, the RA-RNTI associated with the PRACH in which theRandom Access Preamble is transmitted, may be computed in terms of indexof the first OFDM symbol of the specified PRACH, an index of the firstslot of the specified PRACH in a system frame, an index of the specifiedPRACH in the frequency domain, and/or uplink carrier indicator. Forexample, an example RA-RNTI may be calculated as:RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_idwhere s_id may be the index of the first OFDM symbol of the specifiedPRACH (0≤s_id<14), t_id may be the index of the first slot of thespecified PRACH in a system frame (0≤t_id<80), f_id may be the index ofthe specified PRACH in the frequency domain (0≤f_id<8), andul_carrier_id may be the UL carrier used for Msg1 1220 transmission ortwo-step Msg1 1620 (0 for NUL carrier, and 1 for SUL carrier or viceversa).

For example, a wireless device, that transmitted a random accesspreamble, may start to monitor a downlink control channel for a randomaccess response corresponding to the random access preamble. Thepossible occurrence of a measurement gap may not determine when awireless device starts to monitor a downlink control channel.

If a wireless device performs a contention-free random access procedurefor a beam failure recovery request, the wireless device may start arandom access window (e.g., ra-ResponseWindow) configured in a beammanagement configuration parameters (e.g., BeamFailureRecoveryConfig) ata first downlink control channel (e.g., PDCCH) occasion from the end ofthe Random Access Preamble transmission. The wireless device may monitorthe first downlink control channel of the SpCell for a response to beamfailure recovery request identified by the C-RNTI while the randomaccess window is running

If a wireless device down not performs a contention-free random accessprocedure for beam a failure recovery request, the wireless device maystart a random access window (e.g., ra-ResponseWindow) configured in arandom access configuration parameter (e.g., RACH-ConfigCommon) at afirst downlink control channel occasion from an end of a random accesspreamble transmission. The wireless device may monitor the firstdownlink control channel occasion of the SpCell for random accessresponse(s) identified by the RA-RNTI while a random access responsewindow (e.g., ra-ResponseWindow) is running

In an example, a downlink assignment may be received by a wirelessdevice, on the PDCCH for the RA-RNTI and the received TB (e.g., MAC PDUcomprising one or more random access responses is successfully decoded.For example, the MAC PDU may comprise a MAC subPDU with Random AccessPreamble identifier corresponding to a preamble that a wireless devicetransmits to a base station. In this case, the wireless device maydetermine that this random access response reception may be successful.For example, the MAC subPDU may comprise a preamble index (e.g., RAPID)only, e.g., for a random access procedure initiated for a systeminformation request.

The amount of data traffic carried over cellular networks is expected toincrease for many years to come. The number of users/devices isincreasing, and each user/device accesses an increasing number andvariety of services, e.g. video delivery, large files, images. Thisrequires not only high capacity in the network, but also provisioningvery high data rates to meet customers' expectations on interactivityand responsiveness. More spectrum is therefore needed for cellularoperators to meet the increasing demand Considering user expectations ofhigh data rates along with seamless mobility, it is beneficial that morespectrum be made available for deploying macro cells as well as smallcells for cellular systems.

Striving to meet the market demands, there has been increasing interestfrom operators in deploying some complementary access utilizingunlicensed spectrum to meet the traffic growth. This is exemplified bythe large number of operator-deployed Wi-Fi networks and the 3GPPstandardization of interworking solutions with Wi-Fi, e.g., LTE/WLANinterworking. This interest indicates that unlicensed spectrum, whenpresent, may be an effective complement to licensed spectrum forcellular operators to help addressing the traffic explosion in somescenarios, such as hotspot areas. For example, in a legacy system (e.g.,LTE), licensed assisted access (LAA) and/or new radio on unlicensedband(s) (NR-U) may offer an alternative for operators to make use ofunlicensed spectrum while managing one radio network, thus offering newpossibilities for optimizing the network's efficiency.

In an example embodiment, Listen-before-talk (LBT) may be implementedfor transmission in a cell configured in unlicensed band (referred to asa LAA cell and/or a NR-U cell for the sake of convenience, for example,an LAA cell and NR-U cell may be interchangeable and may refer any celloperating in unlicensed band. The cell may be operated as non-standalonewith an anchor cell in a licensed band or standalone without an anchorcell in licensed band). The LBT may comprise a clear channel assessment.For example, in an LBT procedure, equipment may apply a clear channelassessment (CCA) check before using the channel. For example, the CCAcomprise at least energy detection that determines the presence (e.g.,channel is occupied) or absence (e.g., channel is clear) of othersignals on a channel A regulation of a country may impact on the LBTprocedure. For example, European and Japanese regulations mandate theusage of LBT in the unlicensed bands, for example in 5 GHz unlicensedband. Apart from regulatory requirements, carrier sensing via LBT may beone way for fair sharing of the unlicensed spectrum.

In an example embodiment, discontinuous transmission on an unlicensedcarrier with limited maximum transmission duration may be enabled. Someof these functions may be supported by one or more signals to betransmitted from the beginning of a discontinuous downlink transmissionin the unlicensed band Channel reservation may be enabled by thetransmission of signals, by an NR-U node, after or in response togaining channel access based on a successful LBT operation. Other nodesmay receive the signals (e.g., transmitted for the channel reservation)with an energy level above a certain threshold that may sense thechannel to be occupied. Functions that may need to be supported by oneor more signals for operation in unlicensed band with discontinuousdownlink transmission may comprise one or more of the following:detection of the downlink transmission in unlicensed band (includingcell identification) by wireless devices; time and frequencysynchronization of a wireless devices.

In an example embodiment, DL transmission and frame structure design foran operation in unlicensed band may employ subframe, (mini-)slot, and/orsymbol boundary alignment according to carrier aggregation timingrelationships across serving cells aggregated by CA. This may not implythat the base station transmissions start at the subframe, (mini-)slot,and/or symbol boundary. Unlicensed cell operation (e.g., LAA and/orNR-U) may support transmitting PDSCH, for example, when not all OFDMsymbols are available for transmission in a subframe according to LBT.Delivery of necessary control information for the PDSCH may besupported.

An LBT procedure may be employed for fair and friendly coexistence of3GPP system (e.g., LTE and/or NR) with other operators and technologiesoperating in unlicensed spectrum. For example, a node attempting totransmit on a carrier in unlicensed spectrum may perform a clear channelassessment (e.g., as a part of one or more LBT procedures) to determineif the channel is free for use. An LBT procedure may involve at leastenergy detection to determine if the channel is being used. For example,regulatory requirements in some regions, e.g., in Europe, specify anenergy detection threshold such that if a node receives energy greaterthan this threshold, the node assumes that the channel is not free.While nodes may follow such regulatory requirements, a node mayoptionally use a lower threshold for energy detection than thatspecified by regulatory requirements. A radio access technology (e.g.,LTE and/or NR) may employ a mechanism to adaptively change the energydetection threshold. For example, NR-U may employ a mechanism toadaptively lower the energy detection threshold from an upper bound.Adaptation mechanism may not preclude static or semi-static setting ofthe threshold. In an example Category 4 LBT (CAT4 LBT) mechanism orother type of LBT mechanisms may be implemented.

Various example LBT mechanisms may be implemented. In an example, forsome signals, in some implementation scenarios, in some situations,and/or in some frequencies no LBT procedure may be performed by thetransmitting entity. In an example, Category 1 (CAT1, e.g., no LBT) maybe implemented in one or more cases. For example, a channel inunlicensed band may be hold by a first device (e.g., a base station forDL transmission), and a second device (e.g., a wireless device) takesover the for a transmission without performing the CAT1 LBT. In anexample, Category 2 (CAT2, e.g. LBT without random back-off and/orone-shot LBT) may be implemented. The duration of time determining thatthe channel is idle may be deterministic (e.g., by a regulation). A basestation may transmit an uplink grant indicating a type of LBT (e.g.,CAT2 LBT) to a wireless device. CAT1 LBT and CAT2 LBT may be employedfor COT sharing. For example, a base station (a wireless device) maytransmit an uplink grant (resp. uplink control information) comprising atype of LBT. For example, CAT1 LBT and/or CAT2 LBT in the uplink grant(or uplink control information) may indicate, to a receiving device(e.g., a base station, and/or a wireless device) to trigger COT sharing.In an example, Category 3 (CAT3, e.g. LBT with random back-off with acontention window of fixed size) may be implemented. The LBT proceduremay have the following procedure as one of its components. Thetransmitting entity may draw a random number N within a contentionwindow. The size of the contention window may be specified by theminimum and maximum value of N. The size of the contention window may befixed. The random number N may be employed in the LBT procedure todetermine the duration of time that the channel is sensed to be idlebefore the transmitting entity transmits on the channel. In an example,Category 4 (CAT4, e.g. LBT with random back-off with a contention windowof variable size) may be implemented. The transmitting entity may draw arandom number N within a contention window. The size of contentionwindow may be specified by the minimum and maximum value of N. Thetransmitting entity may vary the size of the contention window whendrawing the random number N. The random number N may be used in the LBTprocedure to determine the duration of time that the channel is sensedto be idle before the transmitting entity transmits on the channel

In an unlicensed band, a type of LBT (CAT1, CAT2, CAT3, and/or CAT4) maybe configured via control messages (RRC, MAC CE, and/or DCI) per a cell.In an example, a type of LBT (CAT1, CAT2, CAT3, and/or CAT4) may beconfigured via control messages (RRC, MAC CE, and/or DCI) per BWP. Forexample, a type of LBT (CAT1, CAT2, CAT3, and/or CAT4) may be determinedat least based on a numerology configured in a BWP. In this case, BWPswitching may change a type of LBT.

In an example, a wireless device may employ uplink (UL) LBT. The UL LBTmay be different from a downlink (DL) LBT (e.g. by using different LBTmechanisms or parameters) for example, since the NR-U UL may be based onscheduled access which affects a wireless device's channel contentionopportunities. Other considerations motivating a different UL LBTcomprise, but are not limited to, multiplexing of multiple wirelessdevices in a subframe (slot, and/or mini-slot).

In an example, DL transmission burst(s) may be a continuous (unicast,multicast, broadcast, and/or combination thereof) transmission by a basestation (e.g., to one or more wireless devices) on a carrier component(CC). UL transmission burst(s) may be a continuous transmission from oneor more wireless devices to a base station on a CC. In an example, DLtransmission burst(s) and UL transmission burst(s) on a CC in anunlicensed spectrum may be scheduled in a TDM manner over the sameunlicensed carrier. Switching between DL transmission burst(s) and ULtransmission burst(s) may require an LBT (e.g., CAT1 LBT, CAT2 LBT, CAT3LBT, and/or CAT4 LBT). For example, an instant in time may be part of aDL transmission burst and/or an UL transmission burst.

Channel occupancy time (COT) sharing may be employed in a radio accesstechnology (e.g., LTE and or NR). COT sharing may be a mechanism thatone or more wireless devices share a channel that is sensed as idle byat least one of the one or more wireless devices. For example, one ormore first devices occupy a channel an LBT (e.g., the channel is sensedas idle based on CAT4 LBT) and one or more second devices shares itusing an LBT (e.g., 25 us LBT) within a maximum COT (MCOT) limit. Forexample, the MCOT limit may be given per priority class, logical channelpriority, and/or wireless device specific. COT sharing may allow aconcession for UL in unlicensed band. For example, a base station maytransmit an uplink grant to a wireless device for a UL transmission. Forexample, a base station may occupy a channel and transmit, to one ormore wireless devices a control signal indicating that the one or morewireless devices may use the channel. For example, the control signalmay comprise an uplink grant and/or a particular LBT type (e.g., CAT1LBT and/or CAT2 LBT). The one or more wireless device may determine COTsharing based at least on the uplink grant and/or the particular LBTtype. The wireless device may perform UL transmission(s) with dynamicgrant and/or configured grant (e.g., Type 1, Type2, autonomous UL) witha particular LBT (e.g., CAT2 LBT such as 25 us LBT) in the configuredperiod, for example, if a COT sharing is triggered. A COT sharing may betriggered by a wireless device. For example, a wireless deviceperforming UL transmission(s) based on a configured grant (e.g., Type 1,Type2, autonomous UL) may transmit an uplink control informationindicating the COT sharing (UL-DL switching within a (M)COT). A startingtime of DL transmission(s) in the COT sharing triggered by a wirelessdevice may be indicated by one or more ways. For example, one or moreparameters in the uplink control information indicate the starting time.For example, resource configuration(s) of configured grant(s)configured/activated by a base station may indicate the starting time.For example, a base station may be allowed to perform DL transmission(s)after or in response to UL transmission(s) on the configured grant(e.g., Type 1, Type 2, and/or autonomous UL). There may be a delay(e.g., at least 4 ms) between the uplink grant and the UL transmission.The delay may be predefined, semi-statically configured (via a RRCmessage) by a base station, and/or dynamically indicated (e.g., via anuplink grant) by a base station. The delay may not be accounted in theCOT duration.

In an example, one or more DL to UL and UL to DL switching within ashared COT may be supported. Example LBT requirements to support one ormore switching points, may comprise: for gap of less than a firstthreshold (e.g., 16 us): no-LBT may be used; for gap of above the firstthreshold (e.g., 16 us) but does not exceed a second threshold (e.g., 25us): one-shot LBT may be employed; for single switching point, for thegap from DL transmission to UL transmission exceeds the second threshold(e.g., 25 us): one-shot LBT may be employed; for multiple switchingpoints, for the gap from DL transmission to UL transmission exceeds thesecond threshold (e.g., 25 us), one-shot LBT may be employed.

In an example, a signal that facilitates its detection with lowcomplexity may be useful for wireless device power saving; Improvedcoexistence; Spatial reuse at least within the same operator network,Serving cell transmission burst acquisition, etc. In an example, a radioaccess technology (e.g., LTE and/or NR) may employ a signal comprisingat least SS/PBCH block burst set transmission. Other channels andsignals may be transmitted together as part of the signal. In anexample, the signal may be a discovery reference signal (DRS). There maybe no gap within a time span that the signal is transmitted at leastwithin a beam. In an example, a gap may be defined for beam switching.In an example, the same interlace structure for PUCCH and PUSCH may beused. In an example, interlaced based PRACH may be used.

In an example, initial active DL/UL BWP may be approximately 20 MHz fora first unlicensed band, e.g., in a 5 GHz unlicensed band. An initialactive DL/UL BWP in one or more unlicensed bands may be similar (e.g.,approximately 20 MHz in a 5 GHz and/or 6 GHz unlicensed spectrum), forexample, if similar channelization is used in the one or more unlicensedbands (e.g., by a regulation). For a wideband case, a base station mayconfigure the wideband with one or more BWP. For example, for 80 MHzcase, a base station may configure four BWPs; each BWP may be configuredwith about 20 MHz. An active BWP (DL and/or UL) may be switched one toanother at least based on BWP switching mechanism. For example, a basestation may configure the wideband with one or more subbands. Forexample, for 80 MHz case, a base station may configure four subbands;each subband may be configured with about 20 MHz. For example, awireless device may perform an LBT subband by subband, and may transmitdata via scheduled resources on one or more subbands where the LBTindicates idle.

In an example, HARQ acknowledge and negative acknowledge (A/N) for thecorresponding data may be transmitted in a shared COT (e.g., with a CAT2LBT). In some examples, the HARQ A/N may be transmitted in a separateCOT (e.g., the separate COT may require a CAT4 LBT). In an example, whenUL HARQ feedback is transmitted on unlicensed band, a radio accesstechnology (e.g., LTE and/or NR) may support flexible triggering andmultiplexing of HARQ feedback for one or more DL HARQ processes. HARQprocess information may be defined independent of timing (e.g., timeand/or frequency resource) of transmission. In an example, UCI on PUSCHmay carry HARQ process ID, NDI, RVID. In an example, Downlink FeedbackInformation (DFI) may be used for transmission of HARQ feedback forconfigured grant.

In an example, contention-based random access (CBRA) and/orcontention-free random access (CFRA) may be supported on SpCell. CFRAmay be supported on SCells. In an example, an RAR may be transmitted viaSpCell, e.g., non-standalone scenario. In an example, an RAR may betransmitted via SpCell and/or SCell, e.g., standalone scenario. In anexample, a predefined HARQ process ID for an RAR.

In an example, carrier aggregation between PCell configured on alicensed band and SCell configured on unlicensed band may be supported.In an example, SCell may have both DL and UL, or DL-only. In an example,dual connectivity between PCell (e.g., LTE cell) configured on alicensed band and PSCell (e.g., NR-U cell) configured on unlicensed bandmay be supported. In an example, Stand-alone operation on an unlicensedband, where all carriers are in one or more unlicensed bands, may besupported. In an example, a cell with DL in unlicensed band and UL in alicensed band or vice versa may be supported. In an example, dualconnectivity between PCell (e.g., NR cell) on a licensed band and PSCell(e.g., NR-U cell) on unlicensed band may be supported.

In an example, a radio access technology (e.g., LTE and/or NR) operatingbandwidth may be an integer multiple of 20 MHz, for example, if absenceof Wi-Fi cannot be guaranteed (e.g. by regulation) in an unlicensed band(e.g., 5 GHz, 6 GHZ, and/or sub-7 GHz) where the radio access technology(e.g., LTE and/or NR) is operating. In an example, a wireless device mayperform one or more LBTs in units of 20 MHz. In an example, receiverassisted LBT (e.g., RTS/CTS type mechanism) and/or on-demand receiverassisted LBT (e.g., for example receiver assisted LBT enabled only whenneeded) may be employed. In an example, techniques to enhance spatialreuse may be used.

In an example, wideband carrier with more than one channels (e.g.,subbands) is supported on in an unlicensed band. In an example, theremay be one active BWP in a carrier. In an example, a BWP with one ormore channels may be activated. In an example, when absence of Wi-Ficannot be guaranteed (e.g. by regulation), LBT may be performed in unitsof 20 MHz. In this case, there may be multiple parallel LBT proceduresfor this BWP. The actual transmission bandwidth may be subject tosubband with LBT success, which may result in dynamic bandwidthtransmission within this active wideband BWP.

Channel congestion may cause an LBT failure. For example, theprobability of successful LBT may be increased for random access and/orfor data transmission, for example, if the wireless device selects thecell/BWP/channel with lowest congestion load. For example, channeloccupancy aware RACH procedure may be considered to reduce LBT failure.For example, the random access backoff time for the wireless device maybe adjusted based on channel conditions (e.g., based on channeloccupancy and/or RSSI measurements). For example, a base station may(semi-statically and/or dynamically) transmit a random access backoff.For example, the random access backoff may be predefined. For example,the random access backoff may be incremented after or in response to oneor more random access response reception failures corresponding to oneor more random access preamble attempts.

A base station may transmit a SS/PBCH burst set in one contiguous burst.For example, DRS transmission may comprise SS/PBCH burst set in onecontiguous burst. The base station may transmit one or more CSI-RSsand/or the remaining minimum system information (RMSI)-CORESET(s) and/orthe PDSCH(s) carrying RMSI associated with the SS/PBCH block(s) in thecontiguous burst (e.g., DRS transmission). A base station may transmitone or more messages/signals comprising the SS/PBCH burst, theCSI-RS(s), the RMSI-CORESET(s), and/or the PDSCH(s) carrying RMSI in oneburst in time domain that results in limiting the required number ofchannel access and short channel occupancy in an unlicensed band. Aradio access technology (e.g., LTE and/or NR) may support a stand-aloneoperation and/or dual-connectivity deployments.

A base station (e.g., deployed in an unlicensed band) may transmit DRScomprising signals and/or channels that are required for cellacquisition. For example, the DRS may comprise the transmission of atleast one of reference signals, paging and/or OSI signals. In somescenario and/or radio access technology, a base station may not transmitat least one of following signal(s)/channel(s) in the DRS: RMSI-CORESET,PDSCH and/or CSI-RS

The base station may transmit a DRS within a duration of a DRStransmission window. The DRS transmission window may have a fixed length(e.g. 5 ms) and/or a fixed periodicity (e.g. 20 ms). The length and/orthe periodicity of the DRS transmission window may be semi-staticallyconfigured by a base station. For example, a duration of the DRS (e.g.,comprising SS/PBCH blocks and other multiplex signals/channels)transmitted within the DRS transmission window, may be limited to aparticular time duration (e.g., 1 ms). For example, the duration of theDRS within the window may be limited depending on the periodicity ofDRS. The base station may transmit one or more message indicating anumber of candidate SSB positions within DRS transmission window, e.g.up to 64. The base station may transmit a number of SSBs within DRStransmission window, e.g. up to 8. The transmitted SSBs within the DRSwindow may not overlap in time domain.

Transmission(s) of SS/PBCH block(s) may not be guaranteed (or may beblocked, cancel, rescheduled, postponed, and/or delayed) in unlicensedband due to LBT failure. In an example, one or more SS/PBCH blocks maybe dropped at certain time instances due to LBT failure. Predefinedtransmission position of SS/PBCH block(s) may be in efficient. There maybe a need to opportunistically schedule one or more SS/PBCH block(s),e.g., depending on a success and/or failure of LBT performed on achannel in an unlicensed band. For example, one or more SS/PBCH bursts(e.g., an entire SS/PBCH burst set) may be shifted in time to the nexttransmission instance. For example, a start of a SS/PBCH burst may betruncated and one or more dropped SSB (e.g., due to the truncation) maybe cyclically wrapped at the end of the burst set transmission. Forexample, the network may schedule one or more SSBs and transmit amessage indicating the timing information of scheduled one or more SSBs.For example, SS/PBCH block transmission occasion time index and theassociated SS/PBCH block index may be indicated in the SS/PBCH block toallow the wireless device to derive the timing information.

The base station may determine a COT duration for SS/PBCH bursttransmission. The COT duration may be determined at least based on asubcarrier spacing of the SS/PBCH burst transmission and/or a number ofSS/PBCH blocks in the burst transmission. In an example, the basestation may use CAT2 LBT for the SS/PBCH burst transmission, forexample, that may provide a short COT of 1 ms. A type of LBT may bedetermined based on priorities. In an example, a base station may usehigher priority CAT4 LBT with shorter random backoff, which may providea short COT of 2 ms. In an example, the base station may use lowerpriority CAT4 LBT with longer random backoff, which may provide longerCOT, e.g., up to 10 ms.

Semi-static resource allocation of PRACH may be supported as baselinedesign in a radio access technology (e.g., LTE and/or NR). A basestation may semi-statically configure a wireless device with anassociation between one or more PRACH occasions/preambles and SS/PBCHblock(s). For example, the base station may configure the wirelessdevice with a number of SS/PBCH blocks associated with one PRACHoccasion based on one or more higher layer parameters. A value ofconfigured number of SS/PBCH blocks associated with one PRACH occasionmay be smaller or larger than one. For example, one SS/PBCH block may bemapped to multiple (e.g., consecutive) PRACH occasions, or vice versa. Abase station may support a mapping from different SS/PBCH blocks tonon-overlapping subsets of RACH preamble indices within one PRACHoccasion, for example, if more than one SS/PBCH blocks are mapped to onePRACH occasion.

One or more PRACH periodicities may be supported, e.g., 10, 20, 40, 60,and 160 ms. A wireless device may not wait until the next configuredPRACH occasion without transmitting RACH preamble, for example, if thewireless device determines an LBT failure.

There may be one or more enhancements implemented in a radio accesstechnology (e.g., LTE and/or NR) for an operation in an unlicensed band.In an example, one or more transmission opportunities for PRACH may beconfigured in time, frequency, code, and/or combination thereof. Forexample, a base station may configure a wireless device with one or morePRACH resources across one or more LBT sub-bands/carriers, for example,for contention-free and/or contention-based RA. In the time domain, abase station may configure a wireless device with one or more PRACHresources dynamically, e.g., via DCI for connected mode wireless device.For example, PRACH resources configured to a wireless device maycomprise one or more first PRACH resources dynamically configured (e.g.,via DCI) and/or one or more second PRACH resource semi-staticallyconfigured (e.g., via a RRC message). For example, a base station maydynamically configure one or more PRACH resources within a COT where thebase station transmits one or more SSBs. For example, the one or morePRACH resources may be dynamically scheduled e.g., via paging for idlemode wireless device and/or via DCI (or any control signal) for aconnected mode wireless device. For example, the one or more RACHresources may follow one or more SSBs (e.g., DRS transmission).

A wireless device may transmit one or more preambles. For example, theone or more preambles may be limited before reception of a random accessresponse (e.g., Msg2) in RAR window. For example, the one or morepreambles may be allowed before starting an RAR window. For example, thenumber of allowed preamble transmissions may be predefined or indicatedby a message e.g., RMSI in an RRC message and/or PDCCH order in a DLcontrol signal. In an example, group wise SSB-to-RO mapping may besupported, e.g., by frequency first-time second manner, where groupingis in time domain

A wireless device may perform LBT for accessing a channel beforetransmitting PRACH in an unlicensed band. The wireless device maytransmit the PRACH, for example, if the channel is free. The wirelessdevice may postpone the PRACH transmission, for example, if the channelis busy. A base station may reserve a time duration for the wirelessdevice before transmitting PRACH to perform LBT, e.g., an LBT gap forRACH occasion (RO). The base station may schedule RACH occasions afteror in response to a SS/PBCH burst transmission. Scheduling ROs after orin response to the SS/PBCH burst transmission may help a wireless deviceto avoid LBT failure for the RACH transmission(s). The wireless devicemay assume no interference and/or no hidden nodes after or in responseto detecting SS/PBCH block. The wireless device may skip an LBT andtransmit PRACH in response to a reception of at least one SSB. Thewireless device may transmit at least one preamble without LBT (or withperforming a particular LBT, e.g., CAT2 LBT), for example, if the gapbetween DL/UL switching point (e.g., between a SSB reception andselected RACH resource) is small.

The base station may configure a wireless device with an associationbetween (e.g., SSB-to-RO mapping) SS/PBCH blocks and RACH. For example,a base station may transmit an RRC message indicating the SSB-to-ROmapping that may be time independent. For example, the RRC message mayindicate a frequency resource and/or preamble of a PRACH transmission.The base station may transmit a second message indicating a timeresource of the PRACH transmission. The network may supportcontention-free and contention-based random access procedures on SCells.A base station may transmit a random access response (RAR) on an SCellwhere the base station may receive a preamble. A base station maytransmit a random access response (RAR) on an SCell where a base stationdoes not receive a preamble, e.g., with a cell identifier where the basestation receives the preamble.

A base station may share an acquired COT with a wireless device forrandom access procedure. The base station may allow the wireless deviceto multiplex PRACH resources in UL portion of a acquired COT. Forexample, the base station may transmit, to one or more wireless device,an indication via a group-common PDCCH (GC-PDCCH) to schedule PRACHresources within the acquired COT, e.g., for connected, inactive, and/oridle mode wireless device(s). In an example, the base station maytransmit the PDCCH (e.g., GC-PDCCH) to schedule resources after one ormore SSBs (e.g., in an RMSI and/or in a DCI). In an example, thewireless device may perform one-shot (CAT2) LBT or no LBT for randomaccess preamble (Msg1) and Msg3 transmission in the COT acquired by thebase station, for example, the wireless device receives the indication.

A wireless device may share a COT with a base station, for example, whenthe wireless device acquires the COT, for example, based on CAT4 LBT.For example, the wireless device may acquire the COT for Msg1 and/orMsg3 transmission(s). The base station may perform one-shot (CAT2) LBTor no LBT before Msg2 and Msg4 transmission in the COT. For a two-stepRA procedure, a wireless device may acquire the COT for MsgA (e.g.,preamble(s), and/or UL data) transmission. The base station may performone-shot (CAT2) LBT or no LBT before MsgB (e.g., RAR(s) and/orcontention resolution) transmission in the COT

A base station may configure one or more wireless devices to share oneor more RACH resources. The one or more wireless devices may block eachother, for example, if the one or more wireless devices transmit one ormore preambles without UL synchronization in the same RACH resource. Forexample, a preamble transmission time may vary between wireless devices,for example, if the wireless devices are not UL-synchronized, and/or ifthe wireless devices select different values of backoff timers. The basestation may perform an LBT to reserve RACH resources. The RACH resourcesmay be within the base-station-initiated COT. The channel prior to theRACH resource may be occupied by the base station. The wireless devicemay assume that the channel is reserved by the base station for RACHtransmission and may skip LBT, for example when the channel prior to theRACH resource is occupied by the serving gNB, and/or the RACH resourceis within the COT of the gNB. The base station may indicate the aboveinformation to the wireless device, for example using an initial signal.The initial signal may comprise COT sharing indication.

The base station may perform an LBT and transmit a polling indication toone or more wireless devices, for example, in response to a success ofthe LBT. The one or more wireless devices may transmit one or morepreambles with for example, one-shot (CAT2) LBT or with a high priorityCAT4 LBT performed in response to receiving the polling indication. Oneor more PRACH occasions may follow the polling indication in the COTthat a base station acquired. The wireless device may be configured totransmit a preamble (e.g., Msg1) with a particular LBT (e.g., one-shotLBT) after or in response to receiving the polling indication from thebase station. For example, a reception of the polling indication may bea reference time of one or more preamble transmissions for the one ormore wireless devices. A base station may configure one or more wirelessdevices to transmit at least one preamble (e.g., Msg1) without LBT orwith a particular LBT after or in response to receiving the pollingindication (e.g., being polled by the base station).

In an example, one or more active BWPs may be supported. To improve theBWP utilization efficiency, the BWP bandwidth may be the same as thebandwidth of subband for LBT, e.g., LBT may be carried out on each BWP.The network may activate/deactivate the BWPs based on data volume to betransmitted.

In an example, one or more non-overlapped BWPs may be activated for awireless device within a wide component carrier, which may be similar ascarrier aggregation. To improve the BWP utilization efficiency, the BWPbandwidth may be the same as the bandwidth of subband for LBT, i.e. LBTmay be a carrier out on each BWP. When more than one subband LBTsuccess, it requires a wireless device to have the capability to supportone or more narrow RF or a wide RF which may comprise the one or moreactivated BWPs.

In an example, a single wideband BWP may be activated for a wirelessdevice within a component carrier. The bandwidth of wideband BWP may bein the unit of subband for LBT. For example, if the subband for LBT is20 MHz in 5 GHz band, the wideband BWP bandwidth may comprise multiple20 MHz. The actual transmission bandwidth may be subject to subband withLBT success, which may result in dynamic bandwidth transmission withinthis active wideband BWP.

In an example, active BWP switching may be achieved by use of schedulingDCI. In an example, the network may indicate to a wireless device a newactive BWP to use for an upcoming, and any subsequent, datatransmission/reception. In an example, a wireless device may monitormultiple, configured BWPs to determine which has been acquired for DLtransmissions by the base station. For example, a wireless device may beconfigured with monitoring occasion periodicity and offset for eachconfigured BWP. The wireless device may attempt to determine if a BWPhas been acquired by the base station during those monitoring occasions.In an example, upon determining that the channel is acquired, thewireless device may continue with that BWP as its active BWP, at leastuntil indicated otherwise or Maximum Channel Occupancy Time (MCOT) hasbeen reached. In an example, when a wireless device has determined thata BWP is active, it may attempt blind detection of PDCCH in configuredCORESETs and it might also perform measurements on aperiodic or periodicresources (e.g., Type 1 or Type 2 configured grant).

A base station may configure a wireless device with a carrieraggregation with at least one SCell operating in an unlicensed band. Aconfigured set of serving cells for the wireless device may comprise atleast one SCell operating in the unlicensed band according to aparticular frame structure (e.g., frame structure Type 3 in LTE).

In a RA procedure, a wireless device may receive from a base station atleast one RAR as a response of Msg1 1220 or two-step Msg1 1620. The atleast one RAR may be scrambled by a particular radio network temporaryidentifier (e.g., RA-RNTI). The wireless device may monitor a searchspace set (e.g., the Type1-PDCCH common search space) for a firstdownlink control information (e.g., DCI format 1_0). The first downlinkcontrol information may comprise the at least one RAR. For example, abase station may transmit the at least one RAR in a form of DCI format1_0 for a random access procedure initiated by PDCCH order, MAC layer,and/or RRC layer. For example, the DCI format 1_0 may comprise at leastone of the following fields: one or more random access preamble index,SS/PBCH index, PRACH mask index, UL/SUL indicator, frequency and timedomain resource assignments, modulation and/or coding schemes.

A wireless device may monitor for the first downlink control information(e.g., DCI format 1_0) during a time window. The time window may beindicated by the one or more RRC messages. The time window may start ata first symbol of a first control resource set. The wireless device maybe configured by the one or more parameters in the one or more RRCmessages to receive the first downlink control information on the firstcontrol resource set. The wireless device may determine a length of thetime window based on the one or more parameters in the one or more RRCmessages (e.g., ra-ResponseWindow). The length of the time window may bein number of slots.

The wireless device may stop the time window after or in response to areception of the one or more random access responses being determined assuccessful. A reception of the one or more random access responses maybe determined as successful, for example, when the one or more randomaccess responses comprise a preamble index (e.g., a random accesspreamble identity: RAPID) corresponding to a preamble that the wirelessdevice transmits to a base station. For example, the RAPID may beassociated with the PRACH transmission. The one or more random accessresponses may comprise an uplink grant indicating one or more uplinkresources granted for the wireless device. The wireless device maytransmit one or more transport blocks (e.g., Msg 3) via the one or moreuplink resources.

An RAR may be in a form of MAC PDU comprising one or more MAC subPDUsand/or optionally padding. FIG. 19A is an example of an RAR. A MACsubheader may be octet aligned. Each MAC subPDU may comprise at leastone of following: a MAC subheader with Backoff Indicator only; a MACsubheader with RAPID only (i.e. acknowledgment for SI request); a MACsubheader with RAPID and MAC RAR. FIG. 19B is an example of a MACsubheader with backoff indicator. For example, a MAC subheader withbackoff indicator comprise one or more header fields, e.g., E/T/R/R/BIas described in FIG. 19B. A MAC subPDU with backoff indicator may beplaced at the beginning of the MAC PDU, for example, if the MAC subPDUcomprises the backoff indicator. MAC subPDU(s) with RAPID only and MACsubPDU(s) with RAPID and MAC RAR may be placed anywhere after MAC subPDUwith Backoff Indicator and, if exist before padding as described in FIG.19A. A MAC subheader with RAPID may comprise one or more header fields,e.g., E/T/RAPID as described in FIG. 19C. Padding may be placed at theend of the MAC PDU if present. Presence and length of padding may beimplicit based on TB size, size of MAC subPDU(s).

In an example one or more header fields in a MAC subheader may indicateas follow: an E field may indicate an extension field that may be a flagindicating if the MAC subPDU including this MAC subheader is the lastMAC subPDU or not in the MAC PDU. The E field may be set to “1” toindicate at least another MAC subPDU follows. The E field may be set to“0” to indicate that the MAC subPDU including this MAC subheader is thelast MAC subPDU in the MAC PDU; a T filed may be a flag indicatingwhether the MAC subheader contains a Random Access Preamble ID or aBackoff Indicator (one or more backoff values may predefined and BI mayindicate one of backoff value). The T field may be set to “0” toindicate the presence of a Backoff Indicator field in the subheader(BI). The T field may be set to “1” to indicate the presence of a RandomAccess Preamble ID field in the subheader (RAPID); an R filed mayindicate a reserved bit that may be set to “0”; a BI field may be abackoff indicator field that identifies the overload condition in thecell. The size of the BI field may be 4 bits; an RAPID field may be aRandom Access Preamble IDentifier field that may identify thetransmitted Random Access Preamble. The MAC subPDU may not comprise aMAC RAR, for example, if the RAPID in the MAC subheader of a MAC subPDUcorresponds to one of the Random Access Preambles configured for SIrequest.

There may be one or more MAC RAR format. At least one of following MACRAR format may be employed in a four-step or a two-step RA procedure.For example, FIG. 20 is an example of one of MAC RAR formats. The MACRAR may be fixed size as depicted in FIG. 20 and may comprise at leastone of the following fields: an R field that may indicate a Reservedbit, set to “0”; a Timing Advance Command field that may indicate theindex value TA employed to control the amount of timing adjustment; a ULGrant field that indicate the resources to be employed on the uplink;and a RNTI field (e.g., Temporary C-RNTI and/or C-RNTI) that mayindicate an identity that is employed during Random Access. For example,for a two-step RA procedure, an RAR may comprise at least one offollowing: a UE contention resolution identity, an RV ID forretransmission of one or more TBs, decoding success or failure indicatorof one or more TB transmission, and one or more fields shown in FIG. 20.

There may be a case that a base station may multiplex, in a MAC PDU,RARs for two-step and four-step RA procedures. If RARs for two-step andfour-step RA procedure have the same size, a wireless device may notrequire an RAR length indicator field and/or the wireless device maydetermine the boundary of each RAR in the MAC PDU based onpre-determined RAR size information. For example, FIG. 21 is an exampleRAR format that may be employed in a MAC PDU multiplexing RARs fortwo-step and four-step RA procedures. The RAR shown in FIG. 21 may be afixed size using the same format for two-step and four-step RAprocedures.

In an example, an RAR for a two-step RA procedure may have a differentformat, size, and/or fields, from an RAR for a four-step RA procedure.For example, FIG. 22A, and FIG. 22B are example RAR formats that may beemployed for a two-step RA procedure. If RARs for two-step and four-stepRA procedures are multiplexed into a MAC PDU, and the RARs havedifferent format between two-step and four-step RA procedure, an RAR mayhave a field to indicate a type of RAR (e.g., a reserved “R” field asshown in FIG. 20, FIG. 22A, and FIG. 22B may be employed to indicate atype of RAR). A field for indicating an RAR type may be in a subheader(such as a MAC subheader) or in an RAR. An RAR may comprise differenttypes of fields that may correspond with an indicator in a subheader orin an RAR. A wireless device may determine the boundary of one or moreRARs in a MAC PDU based on one or more indicators.

In an example, a base station may configure a wireless device with aserving cell comprising one or multiple BWPs. In an example, a maximumnumber of BWP per Serving Cell may be a first number.

In an example, the BWP switching for a Serving Cell may be used toactivate an inactive BWP and deactivate an active BWP at a time. In anexample, the BWP switching may be controlled by the PDCCH indicating adownlink assignment or an uplink grant, by the bwp-InactivityTimer, byRRC signaling, or by the MAC entity itself upon initiation of RandomAccess procedure. In an example, upon/in response to addition of SpCellor activation of an SCell, the DL BWP and UL BWP indicated byfirstActiveDownlinkBWP-Id and firstActiveUplinkBWP-Id respectively maybe active without receiving PDCCH indicating a downlink assignment or anuplink grant. The active BWP for a Serving Cell may be indicated byeither RRC or PDCCH. For unpaired spectrum, a DL BWP may be paired witha UL BWP, and BWP switching may be common for both UL and DL.

In an example, for an activated Serving Cell configured with a BWP, ifthe BWP is activated, the MAC entity may transmit on UL-SCH on the BWP;may transmit on RACH on the BWP; may monitor the PDCCH on the BWP; maytransmit PUCCH on the BWP; may transmit SRS on the BWP; may receiveDL-SCH on the BWP; and may (re-)initialize any suspended configureduplink grants of configured grant Type 1 on the active BWP according tothe stored configuration, if any, and to start in a symbol.

In an example, for an activated Serving Cell configured with a BWP, if aBWP is deactivated, the MAC entity may not transmit on UL-SCH on theBWP; may not transmit on RACH on the BWP; may not monitor the PDCCH onthe BWP; may not transmit PUCCH on the BWP; may not report CSI for theBWP; may not transmit SRS on the BWP; may not receive DL-SCH on the BWP;may clear any configured downlink assignment and configured uplink grantof configured grant Type 2 on the BWP; and may suspend any configureduplink grant of configured grant Type 1 on the inactive BWP.

In an example, upon/in response to initiation of the Random Accessprocedure on a Serving Cell, if PRACH occasions are not configured forthe active UL BWP, the MAC entity may switch the active UL BWP to BWPindicated by initialUplinkBWP and if the Serving Cell is a SpCell, theMAC entity may switch the active DL BWP to BWP indicated byinitialDownlinkBWP. The MAC entity may perform the Random Accessprocedure on the active DL BWP of SpCell and active UL BWP of thisServing Cell.

In an example, upon/in response to initiation of the Random Accessprocedure on a Serving Cell, if PRACH occasions are configured for theactive UL BWP, if the Serving Cell is a SpCell and if the active DL BWPdoes not have the same bwp-Id as the active UL BWP, the MAC entity mayswitch the active DL BWP to the DL BWP with the same bwp-Id as theactive UL BWP. The MAC entity may perform the Random Access procedure onthe active DL BWP of SpCell and active UL BWP of this Serving Cell.

In an example, if the MAC entity receives a PDCCH for BWP switching of aserving cell, if there is no ongoing Random Access procedure associatedwith this Serving Cell; or if the ongoing Random Access procedureassociated with this Serving Cell is successfully completed uponreception of this PDCCH addressed to C-RNTI the MAC entity may performBWP switching to a BWP indicated by the PDCCH.

In an example, if the MAC entity receives a PDCCH for BWP switching fora Serving Cell while a Random Access procedure associated with thatServing Cell is ongoing in the MAC entity, it may be up to a wirelessdevice implementation whether to switch BWP or ignore the PDCCH for BWPswitching, except for the PDCCH reception for BWP switching addressed tothe C-RNTI for successful Random Access procedure completion in whichcase the wireless device may perform BWP switching to a BWP indicated bythe PDCCH. In an example, upon/in response to reception of the PDCCH forBWP switching other than successful contention resolution, if the MACentity decides to perform BWP switching, the MAC entity may stop theongoing Random Access procedure and may initiate a Random Accessprocedure on the new activated BWP; if the MAC decides to ignore thePDCCH for BWP switching, the MAC entity may continue with the ongoingRandom Access procedure on the active BWP.

In an example, if the bwp-InactivityTimer is configured, if thedefaultDownlinkBWP is configured, and the active DL BWP is not the BWPindicated by the defaultDownlinkBWP; or if the defaultDownlinkBWP is notconfigured, and the active DL BWP is not the initialDownlinkBWP, if aPDCCH addressed to C-RNTI or CS-RNTI indicating downlink assignment oruplink grant is received on the active BWP; or if a PDCCH addressed toC-RNTI or CS-RNTI indicating downlink assignment or uplink grant isreceived for the active BWP; or if a MAC PDU is transmitted in aconfigured uplink grant or received in a configured downlink assignment:if there is no ongoing random access procedure associated with thisServing Cell; or if the ongoing Random Access procedure associated withthis Serving Cell is successfully completed upon reception of this PDCCHaddressed to C-RNTI, the MAC entity may for each activated Serving Cellmay start or restart the bwp-InactivityTimer associated with the activeDL BWP.

In an example, if the bwp-InactivityTimer is configured, if thedefaultDownlinkBWP is configured, and the active DL BWP is not the BWPindicated by the defaultDownlinkBWP; or if the defaultDownlinkBWP is notconfigured, and the active DL BWP is not the initialDownlinkBWP, if aPDCCH for BWP switching is received on the active DL BWP, and the MACentity switches the active BWP, the MAC entity may for each activatedServing Cell may start or restart the bwp-InactivityTimer associatedwith the active DL BWP.

In an example, if the bwp-InactivityTimer is configured, if thedefaultDownlinkBWP is configured, and the active DL BWP is not the BWPindicated by the defaultDownlinkBWP; or if the defaultDownlinkBWP is notconfigured, and the active DL BWP is not the initialDownlinkBWP, ifRandom Access procedure is initiated on this Serving Cell, the MACentity may for each activated Serving Cell may stop thebwp-InactivityTimer associated with the active DL BWP of this ServingCell, if running. In an example, if the Serving Cell is SCell, the MACentity may stop the bwp-InactivityTimer associated with the active DLBWP of SpCell, if running.

In an example, if the bwp-InactivityTimer is configured, if thedefaultDownlinkBWP is configured, and the active DL BWP is not the BWPindicated by the defaultDownlinkBWP; or if the defaultDownlinkBWP is notconfigured, and the active DL BWP is not the initialDownlinkBWP, if thebwp-InactivityTimer associated with the active DL BWP expires, if thedefaultDownlinkBWP is configured, the MAC entity may perform BWPswitching to a BWP indicated by the defaultDownlinkBWP, otherwise theMAC entity may perform BWP switching to the initialDownlinkBWP.

In an example, a wireless device configured for operation in bandwidthpart(s) (BWPs) of a serving cell, may be configured by higher layers forthe serving cell a set of at most X (e.g., four) bandwidth parts (BWPs)for receptions by the wireless device (DL BWP set) in a DL bandwidth bya parameter (e.g., BWP-Downlink) and a set of at most Y (e.g., four)BWPs for transmissions by the wireless device (UL BWP set) in an ULbandwidth by a parameter (e.g., BWP-Uplink) for the serving cell.

An initial active DL BWP may be defined by a location and number ofcontiguous PRBs, a subcarrier spacing, and a cyclic prefix, for thecontrol resource set for Type0-PDCCH common search space. For operationon the primary cell or on a secondary cell, a wireless device may beprovided an initial active UL BWP by higher layer parameterinitialuplinkBWP. If the wireless device is configured with asupplementary carrier, the wireless device may be provided an initial ULBWP on the supplementary carrier by higher layer parameter (e.g.,initialUplinkBWP) in supplementaryUplink.

In an example, if a wireless device has dedicated BWP configuration, thewireless device may be provided by a higher layer parameter (e.g.,firstActiveDownlinkBWP-Id) a first active DL BWP for receptions and by ahigher layer parameter (e.g., firstActiveUplinkBWP-Id) a first active ULBWP for transmissions on the primary cell.

In an example, for each DL BWP or UL BWP in a set of DL BWPs or UL BWPs,respectively, the wireless device may be configured the followingparameters for the serving cell: a subcarrier spacing provided by ahigher layer parameter (e.g., subcarrierSpacing); a cyclic prefixprovided by a higher layer parameter (e.g., cyclicPrefix); a first PRBand a number of contiguous PRBs indicated by a higher layer parameter(e.g., locationAndBandwidth) that is interpreted as RIV, setting N_(BWP)^(size)=275, and the first PRB is a PRB offset relative to the PRBindicated by higher layer parameters (e.g., offsetToCarrier andsubcarrierSpacing); an index in the set of DL BWPs or UL BWPs byrespective a higher layer parameter (e.g., bwp-Id); a set of BWP-commonand a set of BWP-dedicated parameters by higher layer parameters (e.g.,bwp-Common and bwp-Dedicated).

In an example, for unpaired spectrum operation, a DL BWP from the set ofconfigured DL BWPs with index provided by higher layer parameter (e.g.,bwp-Id) for the DL BWP is linked with an UL BWP from the set ofconfigured UL BWPs with index provided by higher layer parameter (e.g.,bwp-Id) for the UL BWP when the DL BWP index and the UL BWP index areequal. In an example, for unpaired spectrum operation, a wireless devicemay not expect to receive a configuration where the center frequency fora DL BWP is different than the center frequency for an UL BWP when thebwp-Id of the DL BWP is equal to the bwp-Id of the UL BWP.

In an example, for each DL BWP in a set of DL BWPs on the primary cell,a wireless device may be configured control resource sets for every typeof common search space and for wireless device-specific search space. Inan example, the wireless device may not expect to be configured withouta common search space on the PCell, or on the PSCell, in the active DLBWP.

In an example, for each UL BWP in a set of UL BWPs, the wireless devicemay be configured resource sets for PUCCH transmissions.

In an example, a wireless device may receive PDCCH and PDSCH in a DL BWPaccording to a configured subcarrier spacing and CP length for the DLBWP. A wireless device may transmit PUCCH and PUSCH in an UL BWPaccording to a configured subcarrier spacing and CP length for the ULBWP.

In an example, if a bandwidth part indicator field is configured in DCIformat 1_1, the bandwidth part indicator field value may indicate theactive DL BWP, from the configured DL BWP set, for DL receptions. In anexample, if a bandwidth part indicator field is configured in DCI format0_1, the bandwidth part indicator field value may indicate the active ULBWP, from the configured UL BWP set, for UL transmissions.

If a bandwidth part indicator field is configured in DCI format 0_1 orDCI format 1_1 and indicates an UL BWP or a DL BWP different from theactive UL BWP or DL BWP, respectively, for each information field in thereceived DCI format 0_1 or DCI format 1_1, in an example, if the size ofthe information field is smaller than the one required for the DCIformat 0_1 or DCI format 1_1 interpretation for the UL BWP or DL BWPthat is indicated by the bandwidth part indicator, respectively, thewireless device may prepend zeros to the information field until itssize is the one required for the interpretation of the information fieldfor the UL BWP or DL BWP prior to interpreting the DCI format 0_1 or DCIformat 1_1 information fields, respectively. In an example, if the sizeof the information field is larger than the one required for the DCIformat 0_1 or DCI format 1_1 interpretation for the UL BWP or DL BWPthat is indicated by the bandwidth part indicator, respectively, thewireless device may use a number of least significant bits of DCI format0_1 or DCI format 1_1 equal to the one required for the UL BWP or DL BWPindicated by bandwidth part indicator prior to interpreting the DCIformat 0_1 or DCI format 1_1 information fields, respectively. In anexample, the wireless device may set the active UL BWP or DL BWP to theUL BWP or DL BWP indicated by the bandwidth part indicator in the DCIformat 0_1 or DCI format 1_1, respectively.

In an example, a wireless device may expect to detect a DCI format 0_1indicating active UL BWP change, or a DCI format 1_1 indicating activeDL BWP change, if a corresponding PDCCH is received within the first X(e.g., 3) symbols of a slot.

In an example, for the primary cell, a wireless device may be providedby a higher layer parameter (e.g., defaultDownlinkBWP-Id) a default DLBWP among the configured DL BWPs. In an example, if a wireless device isnot provided a default DL BWP by higher layer parameterdefaultDownlinkBWP-Id, the default DL BWP may be the initial active DLBWP.

In an example, if a wireless device is configured for a secondary cellwith higher layer parameter defaultDownlinkBWP-Id indicating a defaultDL BWP among the configured DL BWPs and the wireless device isconfigured with higher layer parameter bwp-InactivityTimer indicating atimer value, the wireless device procedures on the secondary cell may besame as on the primary cell using the timer value for the secondary celland the default DL BWP for the secondary cell.

In an example, if a wireless device is configured by higher layerparameter bwp-InactivityTimer a timer value for the primary cell and thetimer is running, the wireless device may increment the timer everyinterval of 1 millisecond for frequency range 1 or every 0.5milliseconds for frequency range 2 if the wireless device does notdetect a DCI format for PDSCH reception on the primary cell for pairedspectrum operation or if the wireless device does not detect a DCIformat for PDSCH reception or a DCI format for PUSCH transmission on theprimary cell for unpaired spectrum operation during the interval.

In an example, if a wireless device is configured by higher layerparameter BWP-InactivityTimer a timer value for a secondary cell and thetimer is running, the wireless device may increment the timer everyinterval of 1 millisecond for frequency range 1 or every 0.5milliseconds for frequency range 2 if the wireless device does notdetect a DCI format for PDSCH reception on the secondary cell for pairedspectrum operation or if the wireless device does not detect a DCIformat for PDSCH reception or a DCI format for PUSCH transmission on thesecondary cell for unpaired spectrum operation during the interval. Inan example, the wireless device may deactivate the secondary cell whenthe timer expires.

In an example, if a wireless device is configured by higher layerparameter firstActiveDownlinkBWP-Id a first active DL BWP and by higherlayer parameter firstActiveUplinkBWP-Id a first active UL BWP on asecondary cell or supplementary carrier, the wireless device uses theindicated DL BWP and the indicated UL BWP on the secondary cell as therespective first active DL BWP and first active UL BWP on the secondarycell or supplementary carrier.

In an example, for paired spectrum operation, a wireless device does notexpect to transmit HARQ-ACK information on a PUCCH resource indicated bya DCI format 1_0 or a DCI format 1_1 if the wireless device changes itsactive UL BWP on the PCell between a time of a detection of the DCIformat 1_0 or the DCI format 1_1 and a time of a corresponding HARQ-ACKinformation transmission on the PUCCH.

In an example, a wireless device may not expect to monitor PDCCH whenthe wireless device performs RRM over a bandwidth that is not within theactive DL BWP for the wireless device.

In an example, a BWP IE may be used to configure a bandwidth part. In anexample, for each serving cell the network may configure at least aninitial bandwidth part comprising of at least a downlink bandwidth partand one (if the serving cell is configured with an uplink) or two (ifusing supplementary uplink (SUL)) uplink bandwidth parts. Furthermore,the network may configure additional uplink and downlink bandwidth partsfor a serving cell.

In an example, the bandwidth part configuration may be split into uplinkand downlink parameters and into common and dedicated parameters. Commonparameters (in BWP-UplinkCommon and BWP-DownlinkCommon) may be “cellspecific” and the network ensures the necessary alignment withcorresponding parameters of other wireless devices. The commonparameters of the initial bandwidth part of the PCell may be providedvia system information. In an example, the network may provide thecommon parameters via dedicated signaling. Example BWP IE is shownbelow:

BWP ::= SEQUENCE { locationAndBandwidth INTEGER (0..37949),subcarrierSpacingSubcarrierSpacing, cyclicPrefixENUMERATED { extended }OPTIONAL -- Need R } BWP-Uplink ::= SEQUENCE { bwp-Id BWP-Id,bwp-Common BWP-UplinkCommon OPTIONAL, -- Need M bwp-DedicatedBWP-UplinkDedicatedOPTIONAL, -- Need M ... } BWP-UplinkCommon ::=SEQUENCE { genericParameters BWP, rach-ConfigCommon SetupRelease {RACH-ConfigCommon }OPTIONAL, -- Need M pusch-ConfigCommon SetupRelease {PUSCH-ConfigCommon }OPTIONAL, -- Need M pucch-ConfigCommon SetupRelease{ PUCCH-ConfigCommon }OPTIONAL, -- Need M ... } BWP-UplinkDedicated ::=SEQUENCE { pucch-Config SetupRelease { PUCCH-Config } OPTIONAL, -- NeedM pusch-Config SetupRelease { PUSCH-Config } OPTIONAL, -- Cond SetupOnlyconfiguredGrantConfig SetupRelease { ConfiguredGrantConfig } OPTIONAL,-- Need M srs-Config SetupRelease { SRS-Config } OPTIONAL, -- Need MbeamFailureRecoveryConfig SetupRelease { BeamFailureRecoveryConfig}OPTIONAL, -- Cond SpCellOnly ... } BWP-Downlink ::= SEQUENCE {bwp-Id    BWP-Id, bwp-Common BWP-DownlinkCommon OPTIONAL, -- Need Mbwp-Dedicated BWP-DownlinkDedicated OPTIONAL, -- Need M ... }BWP-DownlinkCommon ::= SEQUENCE { genericParameters  BWP,pdcch-ConfigCommon SetupRelease { PDCCH-ConfigCommon } OPTIONAL, -- NeedM pdsch-ConfigCommon SetupRelease { PDSCH-ConfigCommon } OPTIONAL,--Need M ... } BWP-DownlinkDedicated ::= SEQUENCE {pdcch-Config SetupRelease { PDCCH-Config }OPTIONAL, -- Need Mpdsch-Config SetupRelease { PDSCH-Config }OPTIONAL, -- Need Msps-Config  SetupRelease { SPS-Config } OPTIONAL, -- Need MradioLinkMonitoringConfig SetupRelease { RadioLinkMonitoringConfig }OPTIONAL, -- Need M ... }

In an example, cyclic prefix may indicate whether to use the extendedcyclic prefix for this bandwidth part. If not set, the wireless devicemay use the normal cyclic prefix. Normal CP may be supported for allnumerologies and slot formats. Extended CP may be supported only for 60kHz subcarrier spacing. In an example, locationAndBandwidth may indicatefrequency domain location and bandwidth of this bandwidth part. Thevalue of the field may be interpreted as resource indicator value (RIV).The first PRB may be a PRB determined by subcarrierSpacing of this BWPand offsetToCarrier (configured in SCS-SpecificCarrier contained withinFrequencyInfoDL) corresponding to this subcarrier spacing. In case ofTDD, a BWP-pair (UL BWP and DL BWP with the same bwp-Id) may have thesame center frequency. In an example, subcarrierSpacing may indicatesubcarrier spacing to be used in this BWP for all channels and referencesignals unless explicitly configured elsewhere. In an example, the valuekHz15 may corresponds to μ=0, kHz30 to μ=1, and so on. In an example,the values 15, 30, or 60 kHz may be used. In an example, bwp-Id mayindicate an identifier for this bandwidth part. Other parts of the RRCconfiguration may use the BWP-Id to associate themselves with aparticular bandwidth part. A particular BWP ID (e.g., BWP ID=0) may beassociated with the initial BWP and may hence not be used here (in otherbandwidth parts). The base station may trigger the wireless device toswitch UL or DL BWP using a DCI field. The four code points in that DCIfield may map to the RRC-configured BWP-ID as follows: For up to 3configured BWPs (in addition to the initial BWP) the DCI code point maybe equivalent to the BWP ID (initial=0, first dedicated=1, . . . ). Ifthe NW configures 4 dedicated bandwidth parts, they may be identified byDCI code points 0 to 3. In this case it is not possible to switch to theinitial BWP using the DCI field. In an example, bwp-Id may indicate anidentifier for this bandwidth part. Other parts of the RRC configurationmay use the BWP-Id to associate themselves with a particular bandwidthpart. The BWP ID=0 may be associated with the initial BWP and may hencemay not be used here (in other bandwidth parts). The NW may trigger thewireless device to switch UL or DL BWP using a DCI field. The four codepoints in that DCI field map to the RRC-configured BWP-ID as follows:For up to 3 configured BWPs (in addition to the initial BWP) the DCIcode point may be equivalent to the BWP ID (initial=0, firstdedicated=1, . . . ). If the NW configures 4 dedicated bandwidth parts,they may be identified by DCI code points 0 to 3. In this case it maynot be possible to switch to the initial BWP using the DCI field. In anexample, rach-ConfigCommon may indicate configuration of cell specificrandom access parameters which the wireless device may use forcontention based and contention free random access as well as forcontention based beam failure recovery. In an example, the NW mayconfigure SSB-based RA (and hence RACH-ConfigCommon) only for UL BWPs ifthe linked DL BWPs allows the wireless device to acquire the SSBassociated to the serving cell. In an example, PUCCH-config may indicatePUCCH configuration for one BWP of the regular UL or SUL of a servingcell. If the wireless device is configured with SUL, the network mayconfigure PUCCH only on the BWPs of one of the uplinks (UL or SUL).

In an example, the network may configure PUCCH-Config for each SpCell.If supported by the wireless device, the network may configure at mostone additional SCell of a cell group with PUCCH-Config (i.e. PUCCHSCell). In an example, the IE BWP-Id may be used to refer to BandwidthParts (BWP). The initial BWP is referred to by BWP-Id 0. The other BWPsare referred to by BWP-Id 1 to maxNrofBWPs. In an example, theServingCellConfig IE may be used to configure (add or modify) thewireless device with a serving cell, which may be the SpCell or an SCellof an MCG or SCG. In an example, the parameters may be mostly wirelessdevice specific but partly also cell specific (e.g. in additionallyconfigured bandwidth parts). An example, ServingCellConfig IE is shownbelow:

ServingCellConfig ::= SEQUENCE {tdd-UL-DL-ConfigurationDedicated TDD-UL-DL-ConfigDedicated OPTIONAL, --Cond TDD initialDownlinkBWP BWP-DownlinkDedicated OPTIONAL, -- CondServCellAdd downlinkBWP-ToReleaseList SEQUENCE (SIZE (1..maxNrofBWPs))OF BWP-Id OPTIONAL, -- Need N downlinkBWP-ToAddModList SEQUENCE (SIZE(1..maxNrofBWPs)) OF BWP- Downlink OPTIONAL, -- Need NfirstActiveDownlinkBWP-Id BWP-Id OPTIONAL, -- Cond SyncAndCellAddbwp-InactivityTimer ENUMERATED { ms2, ms3, ms4, ms5, ms6, ms8, ms 10,ms20, ms30, ms40,ms50, ms60, ms80, ms100, ms200, ms300, ms500, ms750,ms1280, ms1920, ms2560, spare10, spare9, spare8, spare7, spare6, spare5,spare4, spare3, spare2, spare1 } OPTIONAL, -- Need RdefaultDownlinkBWP-Id BWP-Id OPTIONAL, -- Need SuplinkConfig UplinkConfig OPTIONAL, -- Cond ServCellAdd-ULsupplementaryUplink UplinkConfig OPTIONAL, -- Cond ServCellAdd-SULpdcch-ServingCellConfig SetupRelease { PDCCH-ServingCellConfig} OPTIONAL, -- Need M pdsch-ServingCellConfig SetupRelease {PDSCH-ServingCellConfig } OPTIONAL, -- Need Mcsi-MeasConfig SetupRelease { CSI-MeasConfig } OPTIONAL, -- Need MsCellDeactivationTimer ENUMERATED { ms20, ms40, ms80, ms160, ms200,ms240, ms320, ms400, ms480, ms520, ms640, ms720, ms840, ms1280,spare2,spare1} OPTIONAL, -- Cond ServingCellWithoutPUCCHcrossCarrierSchedulingConfig CrossCarrierSchedulingConfig OPTIONAL, --Need M tag-id TAG-Id, ue-BeamLockFunction ENUMERATED{enabled} OPTIONAL, -- Need R pathlossReferenceLinking ENUMERATED{pCell, sCell} OPTIONAL, -- Cond SCellOnlyservingCellMO MeasObjectId OPTIONAL, -- Cond MeasObject ... }UplinkConfig ::= SEQUENCE { initialUplinkBWP BWP-UplinkDedicatedOPTIONAL, -- Cond ServCellAdd uplinkBWP-ToReleaseList SEQUENCE (SIZE(1..maxNrofBWPs)) OF BWP-Id OPTIONAL, -- Need N uplinkBWP-ToAddModListSEQUENCE (SIZE (1..maxNrofBWPs)) OF BWP-Uplink OPTIONAL, -- Need NfirstActiveUplinkBWP-Id BWP-Id OPTIONAL, -- Cond SyncAndCellAddpusch-ServingCellConfig SetupRelease { PUSCH-ServingCellConfig} OPTIONAL, -- Need M carrierSwitching SetupRelease {SRS-CarrierSwitching } OPTIONAL, -- Need M ... }

In an example, the bwp_InactivityTimer may have a duration in ms afterwhich the wireless device may fall back to the default Bandwidth Part.In an example, the value 0.5 ms may be applicable for carriers >6 GHz.In an example, when the network releases the timer configuration, thewireless device may stop the timer without switching to the default BWP.

In an example, defaultDownlinkBWP-Id may correspond to L1 parameter‘default-DL-BWP’. The initial bandwidth part may be referred to byBWP-Id=0. ID of the downlink bandwidth part to be used upon expiry. Thisfield may be wireless device specific. When the field is absent thewireless device may use the initial BWP as default BWP.

In an example, downlinkBWP-ToAddModList may indicate list of additionaldownlink bandwidth parts to be added or modified. In an example,downlinkBWP-ToReleaseList may indicate list of additional downlinkbandwidth parts to be released. In an example, firstActiveDownlinkBWP-Idif configured for an SpCell, may contain the ID of the DL BWP to beactivated upon performing the reconfiguration in which it is received.If the field is absent, the RRC reconfiguration may not impose a BWPswitch (corresponds to L1 parameter ‘active-BWP-DL-Pcell’). Ifconfigured for an SCell, this field may contain the ID of the downlinkbandwidth part to be used upon MAC-activation of an SCell. The initialbandwidth part may be referred to by BWP-Id=0. In an example,initialDownlinkBWP may indicate a dedicated (UE-specific) configurationfor the initial downlink bandwidth-part. In an example,firstActiveUplinkBWP-Id if configured for an SpCell, may contains the IDof the DL BWP to be activated upon performing the reconfiguration inwhich it is received. If the field is absent, the RRC reconfigurationmay not impose a BWP switch (corresponds to L1 parameter‘active-BWP-UL-Pcell’). If configured for an SCell, this field maycontain the ID of the uplink bandwidth part to be used uponMAC-activation of an SCell. The initial bandwidth part may be referredto by BandwidthPartId=0. In an example, initialUplinkBWP may indicate adedicated (UE-specific) configuration for the initial uplinkbandwidth-part.

In an example, a base station may configure a wireless device with oneor more UL carriers associated with one DL carrier of a cell. One of oneor more UL carriers configured with a DL carrier may be referred to as asupplementary uplink (SUL) carrier or a normal UL (NUL or may bereferred to as a non-SUL) carrier. In an example, a base station mayenhance UL coverage and/or capacity by configuring an SUL carrier. Abase station may configure a BWP configuration per an uplink (e.g., peruplink carrier) in a cell. For example, a base station may configure oneor more BWPs on an SUL separately from one or more BWPs on a NUL. A basestation may control an active BWP of an SUL independently of an activeBWP of a NUL. For example, a base station may control two uplinktransmissions on two ULs (e.g., NUL and SUL) to avoid overlapping PUSCHtransmissions in time. For example, SUL and/or NUL may be configured inan unlicensed band. A base station may configure a wireless device withone or more following operations: an SUL in a licensed band and a NUL ina licensed band, an SUL in a licensed band and a NUL in an unlicensedband, an SUL in an unlicensed band and a NUL in a licensed band, and/oran SUL in an unlicensed band and a NUL in an unlicensed band

In an example, a base station may avoid configuring parallel uplinktransmissions via SUL and NUL of a cell, wherein the parallel uplinktransmissions may be PUCCH (and/or PUSCH) via SUL and PUCCH (and/orPUSCH) via NUL. In an example, a base station may transmit one or moreRRC message (e.g., wireless device specific RRC signaling) to(re-)configure a location of a PUCCH on an SUL carrier and/or on a NULcarrier. A base station may transmit, to a wireless device, one or moreRRC messages comprising configuration parameters for a carrier, whereinthe configuration parameters may indicate at least one of random accessprocedure configuration, BWP configurations (e.g., number of DL/UL BWPs,bandwidth and/or index of configured DL/UL BWP, and/or initial, default,and/or active DL/UL BWP), PUSCH configurations, PUCCH configurations,SRS configurations, and/or a power control parameters.

In an example, a base station may configure an SUL carrier and a NULcarrier to support a random access procedure (e.g., initial access). Forexample, as shown in FIG. 12, to support a random access to a cellconfigured with SUL, a base station may configure a RACH configuration1210 of SUL independent of a RACH configuration 1210 of NUL. Forexample, one or more parameters associated with Msg1 1220, Msg 2 1230,Msg 3 1240, and/or contention resolution 1250 via SUL may be configuredindependent of one or more parameters associated with Msg1 1220, Msg 21230, Msg 3 1240, and/or contention resolution 1250 via NUL. Forexample, one or more parameters associated with PRACH transmissions inMsg 1 1220 via SUL may be independent of one or more parametersassociated with PRACH transmission via NUL.

For a random access procedure in an unlicensed band and/or in a licensedband, based on a measurement (e.g., RSRP) of one or more DL pathlossreferences, a wireless device may determine which carrier (e.g., betweenNUL and SUL) to use. For example, a wireless device may select a firstcarrier (e.g., SUL or NUL carrier) if a measured quality (e.g., RSRP) ofDL pathloss references is lower than a broadcast threshold (e.g., an RRCparameter, rsrp-ThresholdSSB-SUL in RACH-ConfigCommon). If a wirelessdevice selects a carrier between SUL carrier and NUL carrier for arandom access procedure, one or more uplink transmissions associatedwith the random access procedure may remain on the selected carrier.

In an example, a base station may configure NUL and SUL with a TAG. Forexample, for an uplink transmission of a first carrier (e.g., SUL) of acell, a wireless device may employ a TA value received during a randomaccess procedure via a second carrier (e.g., NUL) of the cell.

FIG. 23 is an example of a coverage of a cell configured with a DL andtwo ULs. For example, a base station may configure a NUL and DL over afirst frequency (e.g., high frequency). An SUL may be configured over asecond frequency (e.g., low frequency) to support uplink transmission(e.g., in terms of coverage and/or capacity) of a cell. In an example, abroadcast threshold (e.g., an RRC parameter, rsrp-ThresholdSSB-SUL) fora wireless device to select a carrier may be determined such that awireless device located outside a NUL coverage 2310 but inside an SULcoverage 2320 may start a random access procedure via an SUL. A wirelessdevice located inside a NUL coverage 2310 may start a random accessprocedure via a NUL. A wireless device may employ a RACH configurationassociated with a selected carrier for a random access procedure.

In an example, a wireless device may perform a contention based randomaccess procedure and/or a contention free random access procedure. In anexample, a wireless device may perform a random access procedure on anUL selected based on a broadcast threshold (e.g.,rsrp-ThresholdSSB-SUL). For example, this is a case when a base stationdoes not indicate (e.g., explicitly) the wireless device which carrierto start a random access procedure. In an example, a base station mayindicate which carrier a wireless device performs a random accessprocedure by transmitting a RACH configuration with an SUL indicator(e.g., 0 may indicates a NUL carrier, 1 may indicate an SUL carrier orvice versa). In an example, a base station may indicate (e.g.,explicitly) to a wireless device which UL carrier to be employed for acontention free or contention based random access procedure. In anexample, a base station may indicate a contention free random accessprocedure by transmitting a RACH configuration with a dedicated preambleindex. In an example, a base station may indicate a contention basedrandom access procedure by transmitting a RACH configuration without adedicated preamble index.

In an example, it may be beneficial for a network to receive one or moremeasurements of NUL carrier(s) and/or SUL carrier(s) to initiate a(contention free or contention based) random access procedure for awireless device. For example, a base station may configure a wirelessdevice (e.g., a wireless device in RRC Connected) with one or moremeasurements on one or more DL reference signals associated with NULcarrier(s) and/or SUL carrier(s) of a cell.

For example, if a wireless device transmits quality information of oneor more measurements on one or more DL reference signals associated withNUL carrier(s) and/or SUL carrier(s), a base station may select acarrier between NUL carrier(s) and/or SUL carrier(s) based on thequality of the one or more measurements. A base station may indicate, toa wireless device, a selected carrier via RRC signaling (e.g., handover)and/or PDCCH order (e.g., SCell addition) for initiating a (contentionfree or contention based) random access procedure. In an example, e.g.,for load balancing between NUL carrier(s) and/or SUL carrier(s), a basestation may select one of NUL and SUL carrier by taking intoconsideration congestion in NUL carrier(s) and/or SUL carrier(s). Forexample, based on one or more measurement reports associated with NULcarrier(s) and/or SUL carrier(s), a base station may better select acarrier (e.g., NUL or SUL) of a target cell for a (contention free orcontention based) random access procedure for a handover. For example,based on one or more measurement reports associated with NUL carrier(s)and/or SUL carrier(s), a base station may better select a carrier (e.g.,NUL or SUL) of an SCell (e.g., when the SCell is configured with atleast a NUL carrier and an SUL carrier) for a (contention free orcontention based) random access procedure for an SCell addition.

In an example, for a handover of a wireless device, a source basestation may make a decision on a handover to one or more target cells. Asource base station may indicate a handover decision to a target basestation associated with one or more target cells that the source basestation selects. A target base station may indicate to a wireless device(e.g., through a cell of a source gNB) which carrier (between NULcarrier(s) and SUL carrier(s)) to use via a handover command. Forexample, a handover command received by a wireless device may comprisean SUL indicator (e.g., 1 bit) along with one or more RACH parameters(e.g., dedicated preamble index, and/or PRACH mask index), wherein theSUL indicator may indicate if the one or more RACH parameters areassociated with an SUL or NUL carrier.

For example, it may be useful that a source base station informs atarget base station about measured results on NUL carrier(s) and SULcarrier(s), e.g., high frequency carrier(s) and low frequencycarrier(s), so that the target base station determines a carrier onwhich a wireless device may perform a (contention free or contentionbased) random access procedure for a handover. In an example, when asource base station configures DL measurements on one or more cellsassociation with a NUL carrier(s) and/or SUL carrier(s) of a target gNB,the source base station may need to know whether SUL carrier(s) is (are)configured in the target gNB, and/or which carrier is allowed to beemployed for a handover. For example, a target base station may inform asource base station of one or more configurations of NUL carrier(s)and/or SUL carrier(s) of one or more cells in the target gNB. A sourcebase station may configure DL measurement on one or more cells in thetarget gNB, based on one or more configurations indicating carrierconfigurations at the one or more cells in the target gNB.

In an example, for an SCell addition, a base station may be aware ofwhether SUL carrier(s) is (are) configured in an SCell, and/or whichcarrier is allowed to be employed for an SCell addition. A base stationmay configure DL measurements on NUL carrier(s) and/or SUL carrier(s). Abase station may configure a wireless device with one or more RACHconfigurations for an SCell, e.g., a first RACH configuration for an SULcarrier, a second RACH configuration for a NUL carrier, and so on. Abase station may transmit, to a wireless device via a PDCCH ordercomprising a parameter indicating in which carrier the wireless devicestarts a (contention free or contention based) random access procedure.For example, a PDCCH order triggering a (contention free or contentionbased) random access procedure may comprise one or more parametersindicating at least one of at least one preamble (e.g., preamble index),one or more PRACH resources (e.g., PRACH mask index), an SUL indicator,and/or a BWP indicator. For example, for an random access procedure, awireless device receiving a PDCCH order may transmit at least onepreamble via one or more PRACH resources of a BWP indicated by a BWPindicator of a carrier indicated by an SUL indicator.

In an example, a wireless device may determine a random access procedureunsuccessfully completed. For example, if a wireless device receives noRAR corresponding to one or more preambles transmitted by the wirelessdevice during a random access procedure, the wireless device mayconsider the random access procedure unsuccessfully completed. There maybe a number of preamble transmissions allowed during a random accessprocedure (e.g., preambleTransMax in RACH-ConfigGeneric), wherein thenumber of preamble transmissions may be semi-statically configured byRRC. For example, if a wireless device receives no RAR corresponding tothe number of preamble transmissions, the wireless device may consider arandom access procedure unsuccessfully completed. In response to anunsuccessful completion of a random access procedure, a wireless devicemay indicate a problem to upper layer(s), wherein, in response to theindicated problem, the upper layers(s) may trigger radio link failurethat may lead to prolonged random access delay and degraded userexperience.

For example, a base station (source base station and/or a target gNB)configuring a wireless device with a RACH configuration for a randomaccess (for a handover and/or SCell addition) may not allow to reuse theRACH configuration if the random access is unsuccessfully completed.

In an example, a failure of a (contention free or contention based)random access may result in a long delay of random access. For example,if a contention free random access is unsuccessfully completed, insteadof a contention free random access, a wireless device may initiate acontention based random access procedure. For example, if a wirelessdevice fails a contention free random access to a target base stationduring a handover, the wireless device may perform an initial access tothe target base station based on a contention based random access. Awireless device performing a contention based random access proceduremay compete with one or more wireless devices to get an access to a gNB,which may not guarantee a success of the contention based random accessprocedure, and/or which may take long (e.g., four step procedure of thecontention based random access procedure comparing with a contentionfree random access comprising MSG 1 1220 and MSG 2 1230 transmissions)to receive a corresponding RAR.

In an example, if a wireless device fails a contention free randomaccess for an SCell addition, the wireless device may wait until a basestation transmits a message (e.g., PDCCH order) indicating a RACHconfiguration, based on which the wireless device may initiate a randomaccess for an SCell addition. It may take long for a base station todetect a failure of a random access for an SCell addition. A wirelessdevice may wait for a message (e.g., PDCCH order) transmitted a basestation for an SCell addition unnecessarily long.

In an unlicensed band, a failure of a random access may occur due toLBT. For example, in an unlicensed band, at least one LBT may beperformed prior to DL and/or UL transmission. For example, in a randomaccess procedure in FIG. 12, Msg 1 1220, Msg 2 1230, Msg 3 1240, andcontention resolution 1250 may require at least one LBT before thetransmission for contention based random access, e.g., at least 4 LBTs.For contention-free case, Msg 1 1220 and Msg2 1230 may require at leastone LBT, e.g., at least 2 LBTs.

FIG. 24 is an example diagram of contention based and contention-freerandom access procedures with LBT. In an example, a base station and/ora wireless device may not transmit a message (e.g., Msg 1 2420, Msg 22430, Msg 3 2440, and contention resolution 2450) for a random accessprocedure if LBT is failed prior to transmitting the message, e.g., CCAin LBT determines that a channel in unlicensed band is busy (occupied byother device). In an example, a failure of LBT may result in degrading auser experience (e.g., in terms of QoS, capacity (throughput), and/orcoverage). For example, a base station and/or a wireless device may waituntil the channel becomes idle. This may result in a latency problem tomake a radio link connection between a base station and a wirelessdevice. For example, a failure of an LBT during a random accessprocedure may lead a long delay for a wireless device to receive an ULgrant and/or TA value from a base station. This may result in a calldrop and/or traffic congestion. For example, a failure of an LBT in arandom access procedure for an SCell addition may lead a cell congestion(e.g., load imbalancing) on one or more existing cells, e.g., since anSCell may not take over traffic from the one or more existing cells intime.

In an example, there may be a need to improve an efficiency of randomaccess procedure operating in unlicensed band, e.g., to compensate alatency/delay, and/or performance degradation, due to the LBT failure.For example, selecting two or more SSBs and performing one or more LBTson one or more PRACH occasions associated with the two or more SSBs myincrease a success rate of LBT. For example, a wireless device maymeasure a plurality of downlink reference signals (SSBs or CSI-RSs, ifCSI-RS is configured by RRC). The wireless device may select two or moreSSBs by comparing RSRPs of the plurality of downlink reference signalsand a threshold. For example, the threshold may comprisersrp-ThresholdSSB when the plurality of downlink reference signals areSSBs. For example, the threshold may comprise rsrp-ThresholdCSI-RS whenthe plurality of downlink reference signals are CSI-RSs. For example,the wireless device may select two or more downlink referencing signals(SSBs or CSI-RSs) whose RSRPs are higher than the threshold. Forexample, if SSBs are configured with the wireless device, the wirelessdevice may determine one or more PRACH occasions associated with theselected two or more downlink reference signals, e.g., SSBs. Forexample, the wireless device may determine the one or more PRACH basedon an association between PRACH occasions and SSBs that may be indicatedby one or more RRC parameters, e.g., ra-ssb-OccasionMaskIndex. Forexample, if CSI-RSs are configured with the wireless device, thewireless device may determine one or more PRACH occasions associatedwith the selected two or more downlink reference signals, e.g., CSI-RSs.For example, the wireless device may determine the one or more PRACHbased on an association between PRACH occasions and CSI-RSs that may beindicated by one or more RRC parameters, e.g., ra-OccasionList.

In an example, a two-step RA procedure may employ LBT in an unlicensedband. FIG. 25 is an example diagram of a two-step RA procedure with LBT.A base station and/or a wireless device may not transmit a message(e.g., two-step Msg 1 2520, preamble 2530, one or more transport blocks2540, and/or two-step Msg 2 2550) for a random access procedure if LBTis failed prior to transmitting the message, e.g., CCA in LBT determinesthat a channel in unlicensed band is busy (occupied by other device).The transmissions of Preamble 2530 and for one or more transport blocks2540 may have a same LBT and/or different LBTs.

For example, radio resources for transmissions of Preamble 2530 and/orone or more transport blocks 2540 may be configured in a same channel(or a same subband or a same BWP or a same UL carrier), where a wirelessdevice performs an LBT for the transmissions (e.g., based on aregulation). In this case, an LBT result on the same channel (or thesame subband or the same BWP or the same UL carrier) may applied fortransmissions of Preamble 2530 and for one or more transport blocks2540. For example, FIG. 26 is an example of radio resource allocationfor a two-step RA procedure. If a frequency offset in FIG. 26 is zero,PRACH 2930 and UL radio resources 2940 may be time-multiplexed. If atimeoffset in FIG. 26 is zero, PRACH 2930 and UL radio resources 2940may be frequency-multiplexed. The frequency offset in FIG. 26 may be anabsolute number in terms of Hz, MHz, and GHz, and/or a relative number,e.g., one of frequency indices predefined/preconfigured. The timeoffsetin FIG. 26 may be an absolute number in terms of micro-second,milli-second, or second and/or a relative number, e.g., in terms ofsubframe, slot, mini-slot, OFDM symbol. PRACH 2930 for transmission ofpreamble 2530 and UL radio resources for transmission of one or more TBs2540 may be subject to one LBT if f1 2610 and f2 2620 are configured inthe same channel (or a same subband or a same BWP or a same UL carrier).For example, in FIG. 26, one LBT before PRACH 2930 may be performed by awireless device (e.g., based on a regulation of unlicensed band). Forexample, a number of LBTs may be determined based on a value oftimeoffset in FIG. 26. For example, one LBT before PRACH 2930 may beperformed by a wireless device if the value of timeoffset is equal toand/or less than a threshold (that may be configured and/or defined by aregulation). For example, the one LBT determines idle, a wireless devicemay perform a transmission of Preamble 2530 via PRACH 2930 followed by asecond transmission of one or more TBs 2540 via the UL radio resources2940 with no LBT (the transmission order may be switched if the UL radioresources 2940 is allocated before PRACH 2930 in time domain). This maybe a case that PRACH and UL radio resources are allocated closely enoughin time domain. For example, if the value of timeoffset is larger thanthe threshold, a wireless device may perform a first LBT before PRACH2930 and perform a second LBT before Ul radio resources 2940.

A wireless may perform an LBT and apply a result (idle/busy) of the LBTto the transmission of preamble 2530 and UL radio resources fortransmission of one or more TBs 2540. For example, a bandwidth of BWPand/or UL carrier, where f1 2610 and f2 2620 are configured, may belarger than a particular value (e.g., 20 MHz). For example, thebandwidth may be less than the particular value (e.g., 20 MHz). Forexample, a wireless device may perform the transmissions of Preamble2530 and for one or more transport blocks 2540, for example, if thechannel is idle. A transmissions of Preamble 2530 may be followed by atransmission of one or more transport blocks 2540 or vice versa. Atransmissions of Preamble 2530 may be overlapped partially in time witha transmission of one or more transport blocks 2540. A wireless devicemay not perform the transmissions of Preamble 2530 and for one or moretransport blocks 2540, for example, if the channel is busy. A wirelessdevice may perform a particular LBT (e.g., CAT2 LBT) for a firsttransmission followed after or in response to a first transmission.

For example, radio resources for transmissions of Preamble 2530 and oneor more transport blocks 2540 may be configured in different channels(or different subbands or different BWPs or different UL carriers e.g.,one in NUL and the other one in SUL) that may require separate LBTs. Forexample, a wireless device may perform an LBT per one or more channels,per one or more subbands, per one or more BWPs, and/or per one or moreUL carriers. FIG. 27 is an example of one or more LBTs performed for atwo-step RA procedure. In some cases, UL radio resources 2750 may beallocated before or aligned with PRACH 2730 in time. A wireless devicemay perform a first LBT (e.g., LBT 2740 in FIG. 27) before a firsttransmission of preamble 2530 (e.g., via PRACH 2730) and perform asecond LBT (e.g., LBT 2760 in FIG. 27) before a second transmission ofone or more transport blocks 2540 (e.g., via UL radio resources 2750).Depending on results of the first LBT and the second LBT, a wirelessdevice may perform none of, one of, or both of the first transmissionand the second transmission.

For example, the first transmission may be performed when a first resultof the first LBT is idle. The second transmission may be independent ofthe first result. For example, the second transmission may be performedwhen a second result of the second LBT is idle. In this case, there maybe a case that a wireless device may transmit Preamble 2530 in responseto the first LBT being idle and may not be able to transmit one or moretransport blocks 2540 in response to the second LBT being busy. Forexample, a wireless device may not transmit Preamble 2530 in response tothe first LBT being busy and may transmit one or more transport blocks2540 in response to the second LBT being idle. In a two-step RAprocedure, one or more transport blocks may comprise an identifier ofthe wireless device so that a base station may identify which wirelessdevice transmit the one or more transport blocks. The identity may beconfigured by the base station and/or may be at least a portion ofwireless device-specific information, e.g., resume ID, DMRSsequence/index, IMSI, etc. If a wireless device transmits one or moreTBs with no Preamble 2530 (e.g., when a channel, e.g. PRACH 2730 isbusy), a base station may identify the wireless device based on theidentity in the one or more TBs.

In a two-step RA procedure configured in an unlicensed band, theseparate LBTs for transmissions of Preamble and one or more TBs may beperformed in one or more cases. For example, a base station mayconfigure a wireless device with the separate LBTs for a widebandoperation (e.g., for a case that a bandwidth may be larger than 20 MHz).In the wideband operation, a base station may configure a wirelessdevice with a wideband comprising one or more subbands and/or one ormore BWPs. Some of the one or more subbands may be overlapped to eachother at least a portion in frequency domain. Some of the one or moresubbands may not be overlapped to each other at least a portion infrequency domain. Some of the one or more BWPs may be overlapped to eachother at least a portion in frequency domain. Some of the one or moreBWPs may not be overlapped to each other at least a portion in frequencydomain. In a wideband operation, if two radio resources are allocatedwith a space larger than a threshold (e.g., 20 MHz) in frequency domain,separate LBTs may be required for transmissions via the two radioresources. For example, a wideband may comprise one or more subbands,and two radio resources may be allocated in different subbands. In thiscase, a first transmission scheduled in a first subband requires a firstLBT, and a second transmission scheduled in a second subband requires ansecond LBT. The first LBT and the second LBT may be independent of eachother.

For example, UL radio resources for transmission of one or more TBs 2540may be subject to a first LBT (e.g., LBT 2760) and be independent of asecond LBT (e.g., LBT 2740) for transmission of Preamble 2530. Forexample, PRACH 2730 for transmission of Preamble 2530 may be subject toa second LBT (e.g., LBT 2760) and be independent of a first LBT (e.g.,LBT 2760) for transmission of one or more TBs 2540. For example, if f12610 and f2 2620 are configured in different channels (or differentsubbands or different BWPs or different UL carriers), a wireless devicemay perform separate LBTs for a first transmissions of Preamble 2530 anda second transmission of one or more transport blocks 2540.

For example, FIG. 28A and FIG. 28B are examples of one or more LBTsperformed for a two-step RA procedure in an unlicensed band. Theresource allocation and the separate LBTs in FIG. 27 may be resultedfrom FIG. 28A and/or FIG. 28B. For example, a base station may configurea wireless device with one or more PRACH and one or more UL radioresources in different channels (BWPs and/or UL carriers). The wirelessdevice may one or more first opportunities to transmit preambles and oneor more second opportunities to transmit one or more TBs. For example,in FIG. 28A, a wireless device may have two opportunities in PRACH 2830and PRACH 2730 for preamble transmission. Depending on LBT results, awireless device may select one of two opportunities. For example, awireless device may perform a first LBT (e.g., LBT 2840) and a secondLBT (e.g., LBT 2740 in FIG. 28A). If the results of the first and secondLBTs are idle, a wireless device may select one of PRACH associatedeither a first LBT or a second LBT (e.g., based on random selection). Ifone of LBT result is idle and the other of LBT result is busy, awireless device may select PRACH associated with the LBT being idle forpreamble transmission. If the first and second LBTs are busy, a wirelessdevice may not transmit a preamble and may perform one or more LBTs forone or more TB transmissions.

A wireless device may have one or more opportunities for transmission ofone or more TBs via UL radio resources (e.g., in a similar way that awireless device has for preamble transmission above). For example, theone or more opportunities for transmission of one or more TBs may beindependent of one or more opportunities for transmission of preamble.For example, if a wireless device does not transmit a preamble due to aresult (busy) of LBT, the wireless device may perform one or more LBTsto gain access to a channel to transmit one or more TBs. For example, inFIG. 28A, a wireless device may have a first LBT (e.g., LBT 2820)followed by a first transmission opportunity of one or more TBs viafirst UL radio resources 2810 and a second LBT (e.g., LBT 2760 in FIG.28A) followed by a second transmission opportunity of one or more TBsvia second UL radio resources 2750. Depending on LBT results, a wirelessdevice may select one of opportunities. For example, in FIG. 28A, if LBT2820 is busy but LBT 2760 is idle, a wireless device may transmit one ormore TBs via UL radio resources 2750. If one or more LBTs (e.g., LBT2740 and LBT 2840 in FIG. 28A) to gain access for transmitting apreamble are busy, a wireless device may not transmit any preamble. Inthis case, a wireless device may perform one or more second LBTs (e.g.,LBT 2820 and LBT 2760 in FIG. 28A) for transmission of one or more TBs.

For example, before a wireless device initiates a two-step RA procedure,the wireless device may receive, from a base station, control message(s)(e.g., RRC and/or PDCCH) indicating one or more associations betweenPRACH and UL radio resources. The associations may be one-to-one,multi-to-one, one-to-multi, and/or multi-to-multi between one or morePRACHs and one or more UL radio resources. Based on the associations, awireless device may determine which UL radio resources and/or whichPRACH need to be selected. For example, in FIG. 28A, the associationsmay indicate one-to-multi association from PRACH 2730 to UL radioresources 2750 and UL radio resources 2810. For example, theassociations may indicate one-to-one association from PRACH 2830 to ULradio resources 2750. In this case, a wireless device may perform one ormore LBTs (depending on a regulation and/or resource allocation whetherthey are in the same channel) for transmission of one or more TBsdepending on a selection of PRACH. For example, in FIG. 28A, a wirelessdevice may perform two LBTs (LBT 2740 and LBT 2840). If LBT 2740 may beidle but LBT 2840 may be busy, a wireless device transmits a preamblevia PRACH 2730. The wireless device may choose one or more candidate ULradio resources based on a configured association of PRACH 2730, whichmay be one-to-multi from PRACH 2730 to UL radio resources 2750 and ULradio resources 2810. The wireless device may perform LBT 2820 and LBT2760 based on the configured association. Depending on the results ofthe LBTs, a wireless device may transmit one or more TBs. FIG. 28B is anexample of a two-step RA procedure. In this case, UL radio resources isassociated with one PRACH. For example, a base station configured anassociation from PRACH 2730 to UL radio resource 2750 and UL radioresources 2850.

The PRACH and/or Ul radio resources in FIG. 26, FIG. 27, FIG. 28A,and/or FIG. 28B may be associated with at least one reference signalconfiguration (SSB, CSI-RS, DM-RS). A base station may transmit at leastone control message to a wireless device to indicate such anassociation. If the base station transmits a plurality of referencesignals, a configuration of each reference signal has an associationwith at least one PRACH, that may be configured by RRC and/or PDCCH. Indownlink channel, there may be a plurality of PRACHs and a plurality ofUL radio resources associated with the plurality of PRACHs.

In an example, a failure of LBT may result in degrading a userexperience (e.g., in terms of QoS, capacity (throughput), and/orcoverage). For example, a base station and/or a wireless device may waituntil the channel becomes idle. This may result in a latency problem tomake a radio link connection between a base station and a wirelessdevice. For example, a failure of an LBT during a random accessprocedure may lead a long delay for a wireless device to receive an ULgrant and/or TA value from a base station. This may result in a calldrop and/or traffic congestion. For example, a failure of an LBT in arandom access procedure for an SCell addition may lead a cell congestion(e.g., load imbalancing) on one or more existing cells, e.g., since anSCell may not take over traffic from the one or more existing cells intime.

In an example, there may be a need to improve an efficiency of randomaccess procedure operating in unlicensed band, e.g., to compensate alatency/delay, and/or performance degradation, due to the LBT failure.For example, selecting two or more SSBs and performing one or more LBTson one or more PRACH occasions associated with the two or more SSBs myincrease a success rate of LBT. For example, a wireless device maymeasure a plurality of downlink reference signals (SSBs or CSI-RSs, ifCSI-RS is configured by RRC). The wireless device may select two or moreSSBs by comparing RSRPs of the plurality of downlink reference signalsand a threshold. For example, the threshold may comprisersrp-ThresholdSSB when the plurality of downlink reference signals areSSBs. For example, the threshold may comprise rsrp-ThresholdCSI-RS whenthe plurality of downlink reference signals are CSI-RSs. For example,the wireless device may select two or more downlink referencing signals(SSBs or CSI-RSs) whose RSRPs are higher than the threshold. Forexample, if SSBs are configured with the wireless device, the wirelessdevice may determine one or more PRACH occasions associated with theselected two or more downlink reference signals, e.g., SSBs. Forexample, the wireless device may determine the one or more PRACH basedon an association between PRACH occasions and SSBs that may be indicatedby one or more RRC parameters, e.g., ra-ssb-OccasionMaskIndex. Forexample, if CSI-RSs are configured with the wireless device, thewireless device may determine one or more PRACH occasions associatedwith the selected two or more downlink reference signals, e.g., CSI-RSs.For example, the wireless device may determine the one or more PRACHbased on an association between PRACH occasions and CSI-RSs that may beindicated by one or more RRC parameters, e.g., ra-OccasionList.

FIG. 29 is an example of an association between DL reference signals andPRACH occasions. For example, the association may be one-to-one mapping,multi-to-one mapping between DL reference signals and PRACH occasions.For example, in FIG. 29, a wireless device measures k DL referencesignals, and select DL reference signal 1, DL reference signal 2, and DLreference signal 3. For example, if PRACH occasion 1, PRACH occasion 2,and PRACH occasion 3 are associated with DL reference signal 1, DLreference signal 2, and DL reference signal 3, respectively, thewireless device may perform at most 3 LBTs, each LBT is performed priorto each of selected PRACH occasions. For example, a type of LBT may bepre-defined and/or semi-statically by a base station. For example, abase station may indicate a type of LBT of PRACH occasions in a RACHconfiguration. The type may be one of CAT 1, CAT 2, CAT 3, CAT 4 (orlong LBT and/or short LBT).

For example, if an LBT succeed (channel is idle) in a first PRACHoccasion, a wireless device may transmit one or more preambles via thefirst PRACH occasion and may not perform one or more LBTs in other PRACHoccasions that may be available after the first PRACH occasions in thesame PRACH burst. The wireless device may select a PRACH occasion basedon a DL reference signal that the wireless device selects. The DLreference signal may be selected based on a measured received signal,random selection, etc. The wireless device may selection one or more DLreference signals thereby select one or more PRACH occasions associatedwith the one or more DL reference signals. For example, if a wirelessdevice selects PRACH occasion 1, PRACH occasion 3, and LBT on PRACHoccasion 1 is successful, the wireless device may not perform anotherLBT on PRACH occasion 3. For example, if a wireless device selects allPRACH occasions in Freq.1 in FIG. 29, the wireless device may performone or more LBTs prior to each of PRACH occasions in Freq. 1 until anLBT is successful. In response to the LBT being successful, the wirelessdevice may transmit one or more preambles associated with a PRACHoccasion where the LBT was successful. The wireless device may transmitone or more preambles via one or more PRACH occasions selected based onone or more DL reference signals associated with the one or more PRACHoccasions.

For example, if one or more PRACH occasions are FDMed, e.g., PRACHoccasion1 and PRACH occasion 2 in FIG. 29, a wireless device may performone LBT for the one or more PRACH occasions FDMed, which may be firstlyavailable and/or may be randomly selected. For example, a wirelessdevice may, based on RSRPs of DL reference signals, select PRACHoccasion 1 and PRACH occasion 2 FDMed. In this case, the wireless devicemay perform LBTs on PRACH occasion 1 and PRACH occasion 2. If both LBTsare successful, the wireless device may randomly select one of them. Forexample, if both LBTs are successful, the wireless device may select oneavailable first in time domain. For example, if both LBTs aresuccessful, the wireless device may select one whose corresponding DLreference signal's RSRP is higher than the others. For example, PRACHoccasion 1 and PRACH occasion 2 are FDMed within a threshold (less thana bandwidth threshold), the wireless device may perform a wideband LBTthat may cover frequency range of PRACH occasion 1 and PRACH occasion2.In this case if the wideband LBT is successful, the wireless device mayselect one of PRACH occasions based on a random selection, time locationof PRACH occasions, and/or RSRPs of corresponding DL reference signalsas described in this paragraph.

For example, a wireless device may perform a long LBT on a first PRACHoccasion firstly available and perform a short LBT on a second PRACHoccasion followed by the first PRACH occasion if the LBT on the firstPRACH occasion is failed, e.g., long LBT for PRACH occasion 1 and shortLBT for PRACH occasion 3 in FIG. 29. For example, a type of LBT on thesecond PRACH occasion may be configured by a base station. For example,a type of LBT on the second PRACH occasion may be determined by a timedifference of two PRACH occasions. For example, the first PRACH occasionand the second PRACH occasion has a guard time less than a threshold(configurable or pre-defined, e.g., 25 us,or 16 us), the wireless devicemay perform a short LBT on the second PRACH occasion, otherwise performa long LBT.

For example, based on RSRPs of DL reference signals, a wireless devicemay select two or more PRACH occasions. For example, FIG. 29, a wirelessdevice may select PRACH occasion 1, PRACH occasion 2, PRACH occasion 3.Then the wireless device may perform a first LBT on a first PRACHoccasion available firstly in time, e.g., PRACH occasion1. The wirelessdevice may determine a second LBT on a second PRACH occasion in responseto the first LBT. For example, if the first LBT was successful, thewireless device may transmit a preamble via the first PRACH occasion. Ifthe first LBT was not successful, the wireless device may determine toperform a second LBT on a second PRACH occasion available firstly afterthe first PRACH occasion, e.g., PRACH occasion 2. A third LBT on a thirdRACH occasion may be performed if the second LBT on the second PRACHoccasion is failed. For example, the one or more FDMed PRACH occasionsare configured within a guard time less than a threshold, the wirelessdevice may perform a wideband LBT, LBTs on all of the one or more FDMedPRACH occasions.

In an example, a wireless device may transmit a plurality of preamblesvia a plurality of PRACH occasions. In an example, FIG. 29 is an exampleof one or more PRACH occasion configurations. For example, on Freq 1 inFIG. 29, PRACH occasions may be TDMed with a guard time (e.g., a timedifference). In this case, a wireless device may perform an LBT in eachPRACH occasions in Freq 1 for multiple preamble transmissions. Forexample, depending on the guard time between two PRACH occasions, awireless device may perform a long LBT and/or short LBT. For example, ifthe guard time (time difference) is less than a threshold (25 us or 16us), a wireless device may perform a short LBT (or no LBT) on a PRACHoccasion available later than the other, otherwise the wireless devicemay perform long LBT. The type of LBT in each PRACH occasion may beconfigured by an RRC. The type of LBT in each PRACH occasion may bedetermined by a wireless device by comparing with a guard time betweenPRACH occasions and the threshold.

For example, on Freq 2 in FIG. 29, one or more PRACH occasions may beTDMed without a guard time (or with a guard time less than a threshold).In this case, a wireless device may perform an LBT on the first PRACHoccasion occurs firstly among the selected PRACH occasions in Freq 2.For the subsequent PRACH occasions followed by the first PRACH occasionin Freq 2, a wireless device may not perform an LBT if the LBT on thefirst PRACH occasion was successful. In an example, the LBT on the firstPRACH occasion may be a long LBT. An LBT on the subsequent PRACHoccasions may be a short LBT if the LBT on the first PRACH occasion wassuccessful. If the selected PRACH occasions are not contiguous in time,a wireless device may perform a long LBT or a short LBT. For example, atype of LBT is configured by a base station or determined based on atime difference of the selected PRACH occasions non-contiguous. Forexample, on Freq 3 in FIG. 30, one or more PRACH occasions may begrouped without a guard time. For example, there may be a guard timebetween two groups as shown in PRACH occasion f3-2 and PRACH occasionf3-3 in FIG. 30. Similar mechanism determining an LBT in Freq. 2 andFreq.1 may be applied to the grouped PRACH occasions in other frequencybands.

In an unlicensed spectrum, one or more uplink and/or downlinktransmissions may be blocked by an LBT. For example, a wireless deviceand/or a base station may not transmit any message transmission in afour-step random access procedure and/or two-step random accessprocedure if a channel is busy (occupied by other device(s)).

For example, a wireless device may transmit at least one preamble to abase station on an unlicensed spectrum. For example, a wireless devicemay perform one or more LBTs (e.g., for example preamble transmissionsfrom FIG. 24 to FIG. 30). The wireless device may transmit at least onepreamble to a base station when the uplink random access channel is idleon an unlicensed spectrum. At a base station side, a base station mayreceive at least one preamble that a wireless device transmits. The basestation may perform one or more LBTs to transmit at least one randomaccess response corresponding to the at least one preamble. The basestation may perform a second LBT with a certain period of time (e.g.,backoff) if a channel is identified as busy based on a first LBT (thatperformed earlier than the second LBT).

There may be a random access response window where a wireless device maymonitors a downlink control channel for a random access responsetransmitted from a base station as a response to a preamble transmittedby the wireless device. For example, a base station may transmit amessage comprising a value of an RAR window. For example, a messagecomprising a random access configuration parameters (e.g.,RACH-ConfigGeneric) may indicates a value of an RAR window (e.g.,ra-ResponseWindow in RACH-ConfigGeneric). For example, the value of anRAR window may be fixed, for example, to 10 ms or other time value. Forexample, the value of an RAR window may be defined in terms of a numberof slots as shown in RACH-ConfigGeneric. Based on the number of slotsand a numerology configured for a random access procedure, a wirelessdevice may determine a size of an RAR window. For example, inRACH-ConfigGeneric, s110, s120, s140, and s180 may be values ofra-ResponseWindow for numerologies μ=0, μ=1, μ=2, and μ=3 in FIG. 31,respectively. The parameters in each numerology may be limited to thecase in FIG. 31. For example, the parameters in each numerology may bepredefined with different subcarrier spacing, slot duration, and/orcyclic prefix size.

A wireless device may perform one or more retransmission of one or morepreambles during a random access procedure. There may be one or moreconditions at least based on which the wireless device determines theone or more retransmission of one or more preambles. For example, thewireless device determines the one or more retransmission of one or morepreambles when the wireless device determines that a random accessresponse reception is not successful. The wireless device may determinethat a random access response reception is not successful, for example,if at least one random access response comprising one or more randomaccess preamble identifiers that matches the transmitted PREAMBLE_INDEXhas not been received until an RAR window (e.g., ra-ResponseWindowconfigured in RACH-ConfigCommon) expires. The wireless device maydetermine that a random access response reception is not successful, forexample, if a PDCCH addressed to the C-RNTI has not been received on theServing Cell where the preamble was transmitted until a RAR window for abeam failure recovery procedure (e.g., ra-ResponseWindow configured inBeamFailureRecoveryConfig) expires.

For example, a wireless device determines the one or more retransmissionof one or more preambles when the wireless device determines that acontention resolution is not successful. A MAC entity of the wirelessdevice may start a contention resolution timer (e.g.,ra-ContentionResolutionTimer) and may restart the contention resolutiontimer (e.g., ra-ContentionResolutionTimer) at each HARQ retransmissionin the first symbol after the end of a Msg3 transmission, for example,once a wireless device transmits, to a base station, Msg3. The wirelessdevice may monitor a PDCCH while the contention resolution timer (e.g.,ra-ContentionResolutionTimer) is running, e.g., for example, regardlessof the possible occurrence of a measurement gap. A wireless device maystop the contention resolution timer and determine that a contentionresolution is successful, for example, if a notification of a receptionof a PDCCH transmission of a cell (e.g., SpCell) is received from lowerlayers, and the wireless device identifies that the PDCCH transmissionis an indication of a contention resolution corresponding to a Msg3transmission (or MsgB transmission) that the wireless device performed.

A wireless device may determine one or more retransmission of one ormore preambles, for example, if the wireless device determines that acontention resolution is not successful. A wireless device may determinethat a contention resolution is not successful, for example, if thewireless device does not receive an indication of a contentionresolution while a contention resolution timer (e.g.,ra-ContentionResolutionTimer) is running. For example, the wirelessdevice may determine that a contention resolution is not successful, forexample, if the contention resolution timer (e.g.,ra-ContentionResolutionTimer) expires. The wireless device may discard aTEMPORARY_C-RNTI indicated by an RAR in response to an expiry of thecontention resolution timer (and/or in response to the contentionresolution being unsuccessful).

For a two-step RA procedure, a wireless device may determine one or moreretransmission of one or more preambles, for example, if the wirelessdevice may not receive MsgB corresponding to MsgA, for example, during awindow configured to monitor MsgB in one or more DL control channels. Awireless device performing a two-step RA procedure may receive aresponse (e.g., MsgB) indicating a fallback to a four-step RA procedure.In this case, the wireless device may start a timer (e.g.,ra-ContentionResolutionTimer) in response to transmitting one or moreTBs (e.g., Msg3) to a base station. The wireless device may determineone or more retransmission of one or more preambles, for example, if thetimer (e.g., ra-ContentionResolutionTimer).

A wireless device may increment a counter counting a number of preambletransmissions (e.g., PREAMBLE_TRANSMISSION_COUNTER) by 1 in response toa random access response reception being unsuccessful and/or in responseto a contention resolution being unsuccessful. The wireless device maydetermine that a random access procedure is unsuccessfully completedand/or a MAC entity of the wireless device may indicate a random accessproblem to upper layer(s), for example, if the number of preambletransmissions may reach a threshold, (e.g., ifPREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1). The wireless devicemay determine that a random access procedure is not completed (and/orone or more retransmission of one or more preambles), for example, ifthe number of preamble transmissions may not reach a threshold, (e.g.,if PREAMBLE_TRANSMISSION_COUNTER<preambleTransMax+1).

A wireless device may delay a particular period of time (e.g., a backofftime) for performing a retransmission of one or more preamble. Forexample, the wireless device may set the backoff time to 0 ms, forexample, when a random access procedure is initiated. The wirelessdevice may set (or update) the backoff time based on thePREAMBLE_BACKOFF determined by a value in a BI field of the MAC subPDU(e.g., BI field in FIG. 19B). For example, the wireless device may setthe PREAMBLE_BACKOFF to value of the BI field of the MAC subPDU using apredefined table. FIG. 32 is an example of backoff parameter values. Forexample, if the wireless device receives BI indicating index 3 (or 0010in a bit string) in the table of FIG. 32, the wireless device may setthe PREAMBLE_BACKOFF to 30 ms. The wireless device may set thePREAMBLE_BACKOFF to value of the BI field of the MAC subPDU multipliedwith SCALING_FACTOR_BI (e.g., a scaling factor) if a base stationconfigures the wireless device with scalingFactorBI by one or more RRCmessages. The wireless device may set (or update) the PREAMBLE_BACKOFFbased on a BI field, for example, if a downlink assignment has beenreceived on the PDCCH for the RA-RNTI and the received TB issuccessfully decoded, and/or if the Random Access Response comprises aMAC subPDU with Backoff Indicator (BI in FIG. 19B). The wireless devicemay set the PREAMBLE_BACKOFF to 0 ms, for example, if a downlinkassignment has not been received on the PDCCH for the RA-RNTI and/or thereceived TB is not successfully decoded, and/or if the Random AccessResponse does not comprise a MAC subPDU with Backoff Indicator (BI inFIG. 19B).

A wireless device may determine a backoff time based on thePREAMBLE_BACKOFF. For example, the wireless device may determine thebackoff time, for example, if the wireless device determines that arandom access response is not successful and/or a contention resolutionis not successful. The wireless device may employ a particular selectionmechanism to determine the backoff time. For example, the wirelessdevice may determine the backoff time based on a uniform distributionbetween 0 and the PREAMBLE_BACKOFF. The wireless device may employ anytype of distribution to select the backoff time based on thePREAMBLE_BACKOFF. The wireless device may ignore the PREAMBLE_BACKOFF(e.g., a value in BI field in FIG. 19B) and/or may not have a backofftime. For example, the wireless device may determine whether to applythe backoff time to a retransmission of at least one preamble based onan event type initiating the random access procedure (e.g., Beam FailureRecovery request, handover, etc.) and/or a type of the random accessprocedure (e.g., four-step or two-step RA and/or CBRA or CFRA). Forexample, the wireless device may apply the backoff time to theretransmission, for example, if the random access procedure is CBRA(e.g., where a preamble is selected by a MAC entity of the wirelessdevice) and/or if the wireless device determines that a random accessprocedure is not completed based on a random access response receptionbeing unsuccessful. For example, the wireless device may apply thebackoff time to the retransmission, for example, if the wireless devicedetermines that a random access procedure is not completed based on acontention resolution being unsuccessful.

A wireless device may perform a random access resource selectionprocedure (e.g., select at least one SSB or CSI-RS and/or select PRACHcorresponding to at least one SSB or CSI-RS selected by the wirelessdevice), for example, if the random access procedure is not completed.The wireless device may delay the subsequent random access preambletransmission (e.g., or delay to perform a random access resourceselection procedure) by the backoff time.

A radio access technology may allow a wireless device to change (switch)a channel (a BWP, and/or a subband) to transmit at least one preamblefor a retransmission. This may increase a number of preambletransmission opportunities. For example, a base station may transmit, toa wireless device, one or more messages (broadcast messages, and/or RRCmessages) indicating a configuration of the one or more channels (e.g.,BWPs and/or subbands) that one or more PRACH are configured. A wirelessdevice may select one of the one or more channels (e.g., BWPs, and/orsubbands) as a channel (e.g., a BWP and/or a subband) to transmit atleast one first preamble. The wireless device may select the channel(e.g., BWP and/or subband) based on an LBT result. For example, thewireless device performs one or more LBTs on one or more channels, andselect the channel among the channel(s) being sensed as idle. Thewireless device may select the one of channels being sensed as idlebased on, for example, a random selection.

The channel may be defined based on a BWP configuration and/or a subbandconfiguration. For example, a base station may configure a wirelessdevice with one or more initial DL and/or UL BWP. A configuration ofeach of the one or more initial DL and/or UL BWPs may compriseBWP-DownlinkDedicated (e.g., for initial DL BWP) and/orBWP-UplinkDedicated (e.g., for initial UL BWP) configuration that mayindicate at least one of following: subcarrier spacing, cyclic prefix,location and a bandwidth of the each of the one or more initial DLand/or UL BWPs, DL control channel configuration, DL shared channelconfiguration, rach-configuration (e.g., rach-ConfigCommon and/orrach-ConfigDedicated), UL control configuration, and/or UL sharedchannel configuration.

For example, one of (initial) UL BWP(s) may be associated with at leastone of (initial) DL BWP(s). The association may be indicated byconfiguration parameter(s) in the one or more messages transmitted bythe base station and/or predefined. For example, the association may bemade, for example, by an (initial) UL BWP configuration (or an (initial)DL BWP configuration) may comprise a DL BWP index (resp. a UL BWP index)of one of one or more DL BWPs (resp. one of one or more UL BWPs). Theassociation may be made by a predefined rule and/or table. For example,an (initial) UL BWP may have an association with an (initial) DL BWPthat has a same BWP index (e.g., UL BWP #0 with DL BWP #0, UL BWP #1with DL BWP #1, and so on). For example, a wireless device may monitor,for a random access response, a control channel based on theassociation. For example, a wireless device may monitor, for a randomaccess response, a control channel of an (initial) DL BWP associatedwith an (initial) UL BWP where the wireless device transmits at leastone preamble. For example, a wireless device may monitor, for acontention resolution, a control channel of an (initial) DL BWPassociated with an (initial) UL BWP where the wireless device transmitsMsg3.

For example, a wireless device may receive, from a base station, an RRCmessage indicating the association between one of (initial) UL BWP(s)and least one of (initial) DL BWP(s). For example, a serving cellconfiguration (e.g., ServingCellConfigCommon orServingCellConfigCommonSIB) in the RRC message may indicate a BWPconfiguration (e.g., DownlinkConfigCommon or DownlinkConfigCommonSIB forinitial DL BWP and/or UplinkConfigCommonSIB for initial uplink BWP) fora random access procedure. For example, there may be one or more DL/ULBWP pairs, each pair may comprise at least one (initial) DL BWPconfiguration and one or more (initial) UL BWP configuration. Forexample, one (initial) DL BWP configuration and one or more (initial) ULBWP configuration may be paired. The RRC message (and/or the one(initial) DL BWP configuration and/or the serving cell configuration)may comprise parameters indicating one or more transmissions of one ormore SSBs (or CSI-RSs). For example, the one or more SSBs may beconfigured per a BWP (e.g., via the one (initial) DL BWP configuration)and/or per a cell (e.g., via the serving cell configuration). One ormore PRACH resources configured in the one or more (initial) UL BWPconfiguration may be associated with the one or more SSBs. A wirelessdevice may switch (change, and/or select) a UL BWP for a preambleretransmission among the one or more UL BWP associated with the one(initial) DL BWP configuration, for example, if the wireless deviceselects one of the one or more SSBs. A wireless device may select PRACHresource(s) configured in one or more (initial) UL BWPs associated withone or more one or more (initial) DL BWPs. For example, the wirelessdevice may select PRACH resource(s) configured in one or more (initial)UL BWPs associated with one or more one or more (initial) DL BWPs, forexample, if A wireless device may select one or more SSBs from the oneor more (initial) DL BWPs.

In an unlicensed band, a wireless device and/or a base station mayperform an LBT before transmitting each message (e.g., Msg1, Msg2, Msg3,Msg4, MsgA, and/or MsgB). Each message may subject to an LBT failurethat may cause a random access delay/latency. A large delay/latencyduring a random access procedure may result in failing to meet a controlplane requirement. Increasing transmission opportunities configured overa frequency domain (e.g., over one or more channels, BWPs and/orsubbands) may enhance the random access procedure (e.g., improve therandom access delay/latency caused by an LBT failure in an unlicensedband).

For example, a base station may configure a wireless device with aplurality of DL and/or UL BWPs (channels and/or subbands). For a Msg1(e.g., MsgA) transmission, the wireless device may attempt to perform anLBT in one or more UL BWPs configured with RACH resource(s). Once atleast one LBT succeeds on a UL BWP, the wireless device may perform Msg1(e.g., MsgA) transmission via RACH resource(s) in the UL BWP. This mayincrease the probability of LBT success, for example, if each channelstatus of the one or more UL BWPs is independent of each other.

For Msg2/Msg4 (or MsgB) enhancement, a base station may attempt toperform at least one LBT in a plurality of DL BWPs. Once one LBTsucceeds, the base station may perform Msg2/Msg4 (MsgB) transmission. Awireless device may monitor PDCCH in one or more DL BWPs of theplurality of DL BWPs. The one or more DL BWPs may be associated with oneor more UL BWPs where the wireless device transmits at least one Msg1,Msg3 and/or MsgB. The one or more DL BWPs may be predefined and/orsemi-statically configured by a RRC message transmitted by the basestation.

For Msg3 enhancement, a base station may transmit at least one RARcomprising a plurality of UL grants corresponding to a plurality ofBWPs. For example, the at least one RAR may comprises one or more ULgrants, each of the one or more UL grants may comprise one or morefields indicating a BWP identifier and time/frequency domain resource ina BWP corresponding to the BWP identifier. The wireless device mayperform at least one LBT in one or more of indicated BWPs (e.g., theplurality of BWPs). Once one LBT succeeds, the wireless device mayperform Msg3 transmission.

For example, a wireless device may transmit Msg1 and Msg3 via differentchannels (e.g., UL BWPs and/or subbands). For example, a wireless devicemay receive Msg2 and Msg4 via different channels (e.g., DL BWPs and/orsubbands). For example, a wireless device may transmit Msg1 for apreamble retransmission via a channel (e.g., a UL BWP and/or a subband).The channel may be different from a channel where the wireless devicetransmits Msg1 in a previous preamble (re)transmission.

In a radio access technology (e.g., LTE LAA and/or NR unlicensed), abase station may configure multiple preamble transmission opportunitiesover a frequency domain. A wireless device may select a different UL BWP(e.g., a different subband) during one or more retransmissions (e.g.,comprising an initial transmission) of at least one preamble. Forexample, a wireless device may transmit a first preamble via a firstPRACH in a first BWP (or a first subband) for a first (re)transmissionduring an RA procedure. The wireless device may transmit a secondpreamble via a second PRACH in a second BWP (or a second subband) for asecond (re)transmission during the RA procedure. The first BWP (or thefirst subband) may be different from the second BWP (resp. the secondsubband), for example, depending on one or more LBT results at least onthe first and second BWPs (or the first and second subbands). The firstBWP (or the first subband) the second BWP (resp. the second subband) maybe the same, for example, depending on one or more LBT results at leaston the first and second BWPs (or the first and second subbands).

FIG. 33 is an example of one or more preamble transmission opportunitiesconfigured via one or more BWPs (or subbands). A base station maytransmit one or more RRC messages indicating one or more PRACH resourcesfor one or more preamble transmission opportunities on one or more BWPs.The wireless device may select at least one PRACH (and/or at least oneBWP or subband) for at least one preamble transmission. The wirelessdevice may select a different PRACH (and/or different BWP or subband),for example, when the wireless device performs a preambleretransmission. For example, an LBT result may determine a selection ofPRACH. For example, a wireless device may perform one or more LBTsbefore one or more PRACHs (e.g., PRACH 3310, PRACH 3320, PRACH 3330,PRACH 3340). The wireless device may transmit at least one preamble viaat least one PRACH (BWP, and/or subband) where a corresponding LBTsucceeds. For example, the wireless device may determine a plurality ofpreamble transmission opportunities over one or more PRACHs (e.g., PRACH3310, PRACH 3330). The wireless device may select one of the one or morePRACHs, for example, based on a random selection. The wireless devicemay determine a retransmission of at least one preamble, for example, ifthe wireless device determine that a reception of an RAR is notsuccessful and/or a contention resolution is not unsuccessful. Thewireless device may determine one or more preamble transmissionopportunities over one or more PRACHs (e.g., PRACH 3360, PRACH 3380)that may be configured in different BWP(s) (or subband(s)).

For a retransmission of preamble, a wireless device may delay theretransmission of preamble based on a backoff time. In a legacy system,a BI (e.g., BI in FIG. 19B) may subject to a UL BWP (e.g., an initial ULBWP) configured for a random access procedure (e.g., configured in aSIB1 IE). A number of the UL BWP(s) (e.g., the initial UL BWP(s)) may beat most one in a legacy system. In a radio access technology (e.g., LTELAA and/or NR unlicensed), a base station may configure multiplepreamble transmission opportunities over a frequency domain. A wirelessdevice may select a different UL BWP (e.g., a different subband), forexample, each time of one or more retransmissions (e.g., comprising aninitial transmission) of at least one preamble. There may be a need tomanage one or more backoff times of one or more (initial) UL BWPs (orsubbands) that one or more PRACH are configured.

For example, a wireless device may transmit to a base station, at leastone preamble. The wireless device may receive, from a base station, arandom access response comprising a plurality of BIs. For example, asingle MAC subPDU may indicates a single BI. For example, a single MACsubPDU may indicates the plurality of BIs. For example, a plurality ofMAC subPDUs may indicates the plurality of BIs. For example, each of theplurality of BIs may be associated with at least one BWP (and/or atleast one subband). An association may be indicated by a field with a BIfield. For example, each of the plurality of BIs may comprise an BWP (ora subband) index (or indicator) and a BI field. The wireless device maydetermine a backoff value of the BWP (or the subband) based on a valueindicated by the BI field.

FIG. 34A, FIG. 34B, FIG. 34C, FIG. 34D, and FIG. 34E are examples of aMAC subPDU (or an RAR) comprising one or more BIs. FIG. 34A, FIG. 34B,FIG. 34C, FIG. 34D, and FIG. 34E are example of a MAC subPDU comprise atleast one of following: an extension field (E) indicating if the MACsubPDU is a last MAC subPDU or not in a MAC PDU, a type filed (T)indicating whether the MAC subPDU (or subheader) comprises at least oneRAP ID or at least one BI, a reservation filed (R) indicating one ormore reserved bit (R may be set to zero), a backoff indicator field (BI)indicating an overload condition and/or indicating one ofPREAMBLE_BACKOFF (e.g., one of indices indicating backoff parametervalues in FIG. 32), and/or a BWP index field indicating one ofconfigured one or more UL BWPs (e.g., UL BWP or initial UL BWP). In animplementation, one or more fields in FIG. 34A, FIG. 34B, FIG. 34C, FIG.34D, and FIG. 34E may not be used (dropped or omitted). One or morefields in FIG. 34A, FIG. 34B, FIG. 34C, FIG. 34D, and FIG. 34E may bepresented in a different order. A wireless device may transmit at leastone preamble and receive an RAR comprising a MAC subPDU indicating a BIin FIG. 19B. The wireless device may apply the BI to determine a backofftime for a BWP (or subband) where the at least one preamble transmitted.A wireless device may transmit at least one preamble and receive an RARcomprising a MAC subPDU indicating a BI in FIG. 34A. The wireless devicemay apply the BI to determine a backoff time for a BWP (or subband)indicated by BWP ID. For example, a base station may transmit a MAC PDU(an RAR) indicating one or more BIs in one or more MAC subPDUs. Forexample, a wireless device may receive a MAC PDU comprising one or moreMAC subPDUs, each may comprise a BI filed and a BWP ID field (e.g. inFIG. 34A). A wireless device may transmit at least one preamble andreceive an RAR comprising a MAC subPDU indicating a plurality of BIs(e.g., in FIG. 34B, in FIG. 34C, FIG. 34D and/or in FIG. 34E). Forexample, a number of BIs in the MAC subPDU may be the same to or lessthan a number of one or more UL (or DL) BWPs (subbands) configured. FIG.34B is an example of two BIs are indicated in a MAC subPDU. FIG. 34C isan example of four BIs are indicated in a MAC subPDU. For example, awireless device may select one or more PRACH for preamble (re)transmission(s) from one or more BWPs (subbands) among a plurality ofBWPs indicated by a plurality of BWP IDs in the received RAR. A wirelessdevice may receive a MAC subPDU comprising one or more BIs without BWPID. FIG. 34D and FIG. 34E are examples of a MAC subPDU comprising threeand four BIs, respectively, without BWP ID. For example, a mappingbetween a BI and a BWP may be predefined. For example, a BI firstlylocated in a MAC subPDU may be associated with a BWP #0, and a BIsecondly located in a MAC subPDU may be associated with a BWP #1, and soon. A wireless device may receive a MAC PDU (an RAR) comprising one ormore MAC subPDUs. For example, each of one or more MAC subPDUs maycomprise at least one BI and/or at least one BWP ID of the at least oneBI. A wireless device may receive a plurality of MAC PDUs (e.g., RARs)comprising one or more MAC subPDUs. For example, each of one or more MACsubPDUs may comprise at least one BI and/or at least one BWP ID of theat least one BI. In an implementation, a BWP ID may be replaced by afrequency resource indicator (e.g., a channel index, frequency index,PRB index, a subband ID).

FIG. 35 is an example of one or more preamble transmissions with one ormore backoff times. A wireless device may receive, from a base station,at least one RAR indicating one or more BIs of one or more BWPs. Forexample, the at least one RAR may comprise a first BI for a first BWPand a second BI for a second BWP. The wireless device may determine aretransmission of one or more preambles. The retransmission may bedetermined, for example, based on (or in response to) a determination ofa random access procedure being not completed (e.g., a reception of anRAR being unsuccessful and/or a contention resolution beingunsuccessful). The wireless device may determine one or more backofftimes of one or more BWPs (or subbands) based on the one or more BIs inthe at least one RAR. For example, in FIG. 35, the wireless device maydetermine a first backoff time 3510 based on a first BI and a secondtime offset 3520 based on a second BI. Mapping between a BI field and aBWP may be indicated by a BWP ID in the at least one RAR or predefined.The wireless device may perform a retransmission of at least onepreamble transmission with a delay of a time offset. For example, inFIG. 35, the wireless device may attempt to perform a retransmission ofat least one preamble transmission on a PRACH 3530 in a first BWP with adelay of the first backoff time 3510 and/or a PRACH 3540 in a second BWPwith a delay of the second backoff time 3520. A wireless device mayselect at least one preamble retransmission opportunity among one ormore PRACHs (e.g., PRACH 3530 and PRACH 3540) in one or more BWPs (orsubbands, e.g., in BWP1 and BWP 2 in FIG. 35) associated with one ormore BIs in the at least one RAR. A wireless device may select at leastone preamble retransmission opportunity among one or more PRACHs (e.g.,PRACH 3530, PRACH 3540, PRACH 3550, and/or PRACH 3560) in one or moreBWPs (or subbands, e.g., BWP1, BWP2, BWP3, and BWP4 in FIG. 35)configured in one or more RRC messages (e.g., SIB1). For example, awireless device may select at least one preamble retransmissionopportunity among a plurality of PRACHs. For example, the plurality ofPRACHs may comprise at least one PRACH resource (e.g., PRACH 3570)configured within a delay (First backoff time 3510). For example, theplurality of PRACHs may not comprise the at least one PRACH resource(e.g., PRACH 3570) configured within the delay (First backoff time3510). A wireless device may determine, based on a type of a RAprocedure, whether the plurality of PRACHs may or may not comprise theat least one PRACH resource (e.g., PRACH 3570) configured within thedelay (First backoff time 3510). For example, the plurality of PRACHsmay comprise at least one PRACH resource (e.g., PRACH 3570) configuredwithin a delay (First backoff time 3510), for example, for a CFRAprocedure, an RA for a beam failure recovery request, and/or an RA foran SI request. For example, the plurality of PRACHs may not comprise theat least one PRACH resource (e.g., PRACH 3570) configured within thedelay (First backoff time 3510), for example, for a CBRA procedure.

There may be a case that the at least one RAR may not comprise a BI of aBWP that may be activated (or allowed) for the retransmission (e.g.,BWP3 and/or BWP4 in FIG. 35). In this case, a wireless device may selectat least one preamble retransmission opportunity among one or morePRACHs (e.g., PRACH 3530 and PRACH 3540) in one or more BWPs (orsubbands, e.g., in BWP1 and BWP 2 in FIG. 35) associated with one ormore BIs in the at least one RAR.

There may be a case that the at least one RAR (e.g., FIG. 36A) may notcomprise a BI of a BWP (e.g., BWP2 in FIG. 36A) that may be activated(or allowed) for the retransmission (e.g., BWP2 in FIG. 36A). In thiscase, the wireless device may set its corresponding backoff time (e.g.,Second backoff time 3630) based on one of the one or more BIs (e.g., afirst BI in FIG. 36A) in the at least one RAR (e.g., the one of the oneor more BIs may be selected based on a random selection, the one may bea largest or smallest value of the one or more BIs). The wireless devicemay set its corresponding backoff time (e.g., Second backoff time 3630)to a predefined value (e.g., 0 ms). The wireless device may select atleast one preamble retransmission opportunity among one or more PRACHs(e.g., PRACH 3620 and PRACH 3640) in one or more BWPs (or subbands,e.g., BWP1, BWP2 in FIG. 36) configured in one or more RRC messages(e.g., SIB1).

There may be a case that a first RAR (e.g., a first RAR in FIG. 36B) maynot comprise a BI of a BWP (e.g., BWP2 in FIG. 36B) that may beactivated (or allowed) for the retransmission. The wireless device mayset its corresponding backoff time (e.g., second backoff time 3620)based on a second RAR (e.g., Second RAR in FIG. 36B) that the wirelessdevice received previously (e.g., before receiving First RAR in FIG.36B). For example, a wireless device may receive the first RAR and thesecond RAR in a same RA procedure. For example, a wireless device mayreceive the first RAR and the second RAR in a different RA procedure.The second RAR may comprise a second BI corresponding to a second BWP(e.g., BWP2 in FIG. 36B). The wireless device may store aPREAMBLE_BACKOFF indicated by the second BI for the second BWP and mayapply the PREAMBLE_BACKOFF to the second backoff time 3670. The wirelessdevice may set the second backoff time 3670 based on one of the one ormore BIs (e.g., the first BI in FIG. 36B) in the first RAR (e.g., theone of the one or more BIs may be selected based on a random selection,the one may be a largest or smallest value of the one or more BIs), forexample, if there is no stored PREAMBLE_BACKOFF for BWP2. The wirelessdevice may set the second backoff time 3670 to a predefined value (e.g.,0 ms), for example, if there is no stored PREAMBLE_BACKOFF for BWP2. Thewireless device may select at least one preamble retransmissionopportunity among one or more PRACHs (e.g., PRACH 3660, PRACH 3680) inone or more BWPs (or subbands, e.g., BWP1, BWP2 in FIG. 36) configuredin one or more RRC messages (e.g., SIB1).

Examples in FIG. 35, FIG. 36A, and FIG. 36B may be implemented with oneor more LBTs in unlicensed band(s). FIG. 37 is an example of one or moreLBTs performed with one or more backoff times. A wireless device mayperform a preamble retransmission in an unlicensed band. For example,one or more UL BWPs (e.g., four UL BWPs in FIG. 37) may be configured inan unlicensed band for a random access procedure. A wireless device maydetermine when to attempt an LBT. For example, a wireless device mayperform an LBT with (after, and/or in response to) a delay of a backofftime for a preamble (re)transmission. For example, a wireless device mayperform an LBT (e.g., LBT for PRACH 3740) with a delay of a backoff time(e.g., second backoff time 3720) for a preamble (re)transmission, forexample, for a CBRA procedure. For example, a wireless device mayperform an LBT (e.g., LBT for PRACH 3770) regardless of a delay of abackoff time for a preamble (re)transmission, for example, for a CFRAprocedure. A wireless device may select at least one preambleopportunity over a PRACH being sensed as idle by an LBT.

FIG. 38 is an example of a single BI. For example, the example in FIG.35 may be the example in FIG. 38, for example, if the at least one RARcomprises a single BI. FIG. 39 is an example of a single BI. Forexample, the example in FIG. 37 may be the example in FIG. 39, forexample, if the at least one RAR comprises a single BI.

FIG. 40 is an example flowchart of a base station. A base station maymeasure a congestion level of one or more channels (e.g., BWPs, and/orsubbands). For example, the one or more channels may comprise one ormore PRACH resources. The congestion level may be determined based onone or more reports (e.g., key performance indicators) comprising a loadinformation (e.g., interference level, throughput, number of drop calls,number of contentions, etc.). The base station may construct a MAC PDU(e.g., an RAR) comprising at least one BI that indicating a congestionlevel and/or PREAMBLE_BACKOFF of at least one channel (e.g., BWP and/orsubband), for example, if the base station may determine to adjust thecongestion level. The base station may construct a MAC PDU (e.g., anRAR) with no BI, for example, if the base station may not need to adjustthe congestion level. The base station may transmit, to one or morewireless devices, the constructed MAC PDU. The constructed MAC PDU(e.g., an RAR) may be transmitted with one or more transmitting beamsvia one or more frequency/time domain resources.

FIG. 41 is an example flowchart of a wireless device. A wireless devicemay perform (or initiate) a RA procedure. The wireless device maydetermine at least one preamble retransmission on at least one channel(e.g., BWP or subband). The wireless device may determine at least onebackoff time of the at least one channel based on the at least one BI(e.g., based on one or more examples from FIG. 35 to FIG. 39), forexample, if the wireless device may receive, from a base station, atleast one RAR comprising at least one BI. The wireless device may delayattempting to perform the at least one preamble retransmission on the atleast one channel by the at least one backoff time. The wireless devicemay attempt to perform the at least one preamble retransmission on theat least one channel in response to the determining the at least onepreamble retransmission, for example, if the wireless device may notreceive, from a base station, at least one RAR comprising at least oneBI. For example, the at least one preamble retransmission may subject toone or more LBTs in an unlicensed band.

In an example, a wireless device may receive, from a base station, oneor more messages comprising: configuration parameters of a plurality ofsubbands, the plurality of subbands comprising: a first subband; and oneor more second subbands. The wireless device may transmit the at leastone first preamble via first random access resources on the firstsubband. The wireless device may receive a random access responsecomprising a backoff indicator. The wireless device may determine apreamble retransmission. The wireless device may perform, in response todetermining the preamble retransmission: a first channel accessprocedure on the first subband with a delay based on the backoffindicator; and one or more second channel access procedures on the oneor more second subbands. The wireless device may transmit at least onesecond preamble. In an example, the at least one second preamble may betransmitted via second random access resources. In an example, thesecond random access resources may be on one of the plurality ofsubbands being sensed idle. In an example, the wireless device mayselect the first subband among the plurality of subbands. For example,the selecting the first subband among the plurality of subbands may bebased on the first subband being sensed idle. The wireless device maydetermine the first subband in response to the first subband beingsensed idle. In an example, the random access response comprises apreamble identifier corresponding to the at least one first preamble. Inan example, the wireless device may calculate a radio network temporaryidentifier based on time and frequency indices of the at least one ofrandom access channel resources. For example, the random access responseis scrambled by the radio network temporary identifier.

In an example, a wireless device may receive, from a base station, amessage comprising one or more random access configuration parametersindicating a plurality of random access channel occasions in a pluralityof subbands of a cell. The wireless device may transmit, to the basestation, at least one first preamble via a first random access channeloccasion selected among the plurality of the random access channeloccasions. The wireless device may receive a random access responsecomprising a plurality of backoff indicators. For example, each of theplurality of the backoff indicators is associated with one of theplurality of subbands. The wireless device may transmit at least onesecond preamble via a second random access channel occasion. Forexample, the second random access channel occasion may be selected:among the plurality of random access channel occasions; and based on afirst backoff time determined by one of the plurality of backoffindicators associated with a subband of the second random access channeloccasion. In an example, the plurality of subbands are in unlicensedbands. The wireless device may perform one or more listen-before-talks(LBTs) on at least one of the plurality of the random access channeloccasions. For example, the second random access channel occasion issensed to be idle based on at least one of the one or more LBTs. Forexample, the at least one of the one or more LBTs is an LBT success. Forexample, the at least one of the one or more LBTs is an LBT firstlysucceeded among the one or more LBTs. For example, the cell is anunlicensed cell. The wireless device may select the first backoff timeaccording to a uniform distribution between zero and a value indicatedby the one of the plurality of backoff indicators. The wireless devicemay delay the transmitting the at least one second preamble at least bythe first backoff time. The wireless device may apply (or scale, oradjust) the first backoff time based on a scaling factor. For example,the one or more random access configuration parameters indicates thescaling factor. In an example, the random access response comprises asubheader comprising an index indicating the at least one firstpreamble. For example, the one of the plurality of subbands comprise atleast one bandwidth part. For example, at least one bandwidth part maycomprise one of the plurality of subbands.

In an example, a wireless device may receive, from a base station, amessage comprising one or more random access configuration parametersindicating a plurality of random access channel occasions in a pluralityof subbands, the plurality of subbands comprising a first subband and atleast one second subbands. The wireless device may transmit, to the basestation, at least one first preamble via a first random access channeloccasion selected among the plurality of the random access channeloccasions. The wireless device may receive a random access responsecomprising at least one backoff indicator. For example, the at least onebackoff indicator is associated with the first subband. The wirelessdevice may delay a determination selecting: at least one first randomaccess channel occasion in the first subband by a first backoff timedetermined by the at least one backoff indicator; and/or at least onesecond random access channel occasion in the at least one secondsubbands by a second backoff time. The wireless device may transmit atleast one second preamble via a second random access channel occasion.For example, the first subband and the second subband are in unlicensedbands. The wireless device may perform a first listen-before-talks (LBT)for the at least one first random access channel occasion and a secondLBT for the at least one second random access channel occasion. Forexample, the second random access channel occasion may be sensed to beidle based on at least one of the one or more LBTs. For example, thesecond random access channel occasion may be the at least one firstrandom access channel occasion in response to determining that thesecond LBT performed for the at least one second random access channeloccasion may be failed. For example, the second random access channeloccasion may be the at least one first random access channel occasion inresponse to further determining that the first LBT being perform afterthe second LBT. For example, the second random access channel occasionmay be the at least one first random access channel occasion in responseto determining that the first LBT being perform before the second LBT.For example, the second random access channel occasion may be the atleast one second random access channel occasion in response todetermining that the first LBT performed for the at least one firstrandom access channel occasion may be failed. For example, the secondrandom access channel occasion may be the at least one second randomaccess channel occasion in response to further determining that thesecond LBT being perform after the first LBT. For example, the secondrandom access channel occasion may be the at least one second randomaccess channel occasion in response to determining that the second LBTbeing perform before the first LBT. The wireless device may select thefirst backoff time according to a uniform distribution between zero anda value indicated by the at least one backoff indicator. For example,the second backoff time may be a particular value (e.g., zero). Theparticular value may be predefined and/or semi-statically configured bythe base station. The wireless device may select the second backoff timeaccording to a uniform distribution between zero and a value indicatedby the at least one backoff indicator. The wireless device may receive asecond random access response comprising the at least one second backoffindicator. The wireless device may select the second backoff timeaccording to a uniform distribution between zero and a value indicatedby at least one second backoff indicator. For example, the wirelessdevice may receive the second random access response before receivingthe random access response.

In an example, a wireless device may receive, from a base station, oneor more messages comprising configuration parameters of a plurality ofsubbands. The wireless device may transmit at least one preamble viarandom access resources on at least two of the plurality of thesubbands. The wireless device may receive at least one random accessresponse, each comprising at least one backoff indicator. The wirelessdevice may determine a preamble retransmission. The wireless device mayperform, in response to determining the preamble retransmission: a firstchannel access procedure on a first subband of the plurality of subbandswith a delay determined based on at least a first backoff indicator ofthe at least one backoff indicator; and one or more second channelaccess procedures on one or more second subbands of the plurality ofsubbands with delay(s) determined based on at least one second backoffindicator of the at least one backoff indicator. The wireless device maytransmit at least one second preamble. For example, the first channelaccess procedure comprises at least one LBT. For example, the one ormore second channel access procedures comprise at least one LBT.

According to various embodiments, a device such as, for example, awireless device, off-network wireless device, a base station, and/or thelike, may comprise one or more processors and memory. The memory maystore instructions that, when executed by the one or more processors,cause the device to perform a series of actions. Embodiments of exampleactions are illustrated in the accompanying figures and specification.Features from various embodiments may be combined to create yet furtherembodiments.

FIG. 42 is a flow diagram as per an aspect of an example embodiment ofthe present disclosure. At 4210, a wireless device transmits a firstpreamble via a cell. The first preamble may be transmitted for a randomaccess procedure. The cell may comprise a first sub-band and a secondsub-band. At 4220, the wireless device receives a random accessresponse. The random access response is received after or in response totransmitting the first preamble. The random access response indicates afirst backoff indicator. The first backoff indicator indicates a firstbackoff time interval of the first sub-band. The random access responseindicates a second backoff indicator. The second backoff indicatorindicates a second backoff time interval of the second sub-band. At4230, the wireless device determines a preamble retransmission for therandom access procedure. At 4240, the wireless device selects, as abackoff time interval, a shorter one of the first backoff time intervaland the second backoff time interval. At 4250, the wireless deviceperforms, at a time determined based on the backoff time interval, alisten-before-talk procedure.

FIG. 43 is a flow diagram as per an aspect of an example embodiment ofthe present disclosure. At 4310, a base station may receive, for arandom access procedure, a first preamble via a cell. The cell maycomprise a first sub-band and a second sub-band. At 4320, the basestation may transmit a random access response. The random accessresponse may indicate a first backoff indicator. The random accessresponse may indicate a second backoff indicator. The base station mayreceive, at a first time, a second preamble as a preamble retransmissionfor the random access procedure. The first time may be determined basedon a backoff time interval that is a shorter one of a first backoff timeinterval and a second backoff time interval. The first backoff timeinterval of the first sub-band may be determined based on the firstbackoff indicator. The second backoff time interval of the secondsub-band may be determined based on the second backoff indicator.

According to an example embodiment, a wireless device may transmit, fora random access procedure, a first preamble via a cell comprising afirst sub-band and a second sub-band. The wireless device may receive arandom access response. The random access response may indicate a firstbackoff indicator. The first backoff indicator may indicate a firstbackoff time interval of the first sub-band. The random access responsemay indicate a second backoff indicator. The second backoff indicatormay indicate a second backoff time interval of the second sub-band. Thewireless device may determine a preamble retransmission for the randomaccess procedure. The wireless device may select, as a backoff timeinterval, a shorter one of the first backoff time interval and thesecond backoff time interval. The wireless device may perform, at a timedetermined based on the backoff time interval, a listen-before-talkprocedure.

According to an example embodiment, the listen-before-talk procedure maybe performed, on the first sub-band, based on the first backoff timeinterval being shorter than the second backoff time interval. Accordingto an example embodiment, the wireless device may transmit a secondpreamble via the first sub-band. The wireless device may transmit thesecond preamble based on the listen-before-talk procedure indicating thefirst sub-band clear. According to an example embodiment, the wirelessdevice may perform, at a second time, a second listen-before-talkprocedure on the second sub-band. According to an example embodiment,the second time may be determined based on the second backoff timeinterval. According to an example embodiment, the wireless device mayperform the second listen-before-talk procedure based on thelisten-before-talk procedure indicating the first-sub-band occupied.According to an example embodiment, the wireless device may transmit athird preamble via the second sub-band. The wireless device may transmitthe third preamble based on the second listen-before-talk procedureindicating the second sub-band clear. According to an exampleembodiment, there may be no random access channel occasion available onthe first-sub-band between the time and the second time. According to anexample embodiment, there may be at least one random access channeloccasion available on the first-sub-band between the time and the secondtime. According to an example embodiment, the wireless device mayperform, for the at least one random access channel occasion, at leastone third listen-before-talk procedure on the first sub-band. Accordingto an example embodiment, the at least one third listen-before-talkprocedure may indicate the first-sub-band is occupied. According to anexample embodiment, the wireless device may perform, at a third time, atleast one fourth listen-before-talk procedure on the first sub-band.According to an example embodiment, the wireless device may perform thefourth listen-before-talk based on the listen-before-talk procedureindicating the first-sub-band occupied. According to an exampleembodiment, there may be no random access channel occasion available onthe second sub-band between the first time and the third time. Accordingto an example embodiment, the wireless device may transmit a fourthpreamble via the first sub-band. According to an example embodiment, thewireless device may transmit the fourth preamble based on the fourthlisten-before-talk procedure indicating the first sub-band clear.According to an example embodiment, the wireless device may perform atleast one fifth listen-before-talk procedure on the second sub-bandbetween the first time and the third time. According to an exampleembodiment, the at least one fifth listen before-talk procedure mayindicate the second sub-band occupied. According to an exampleembodiment, the at least one fifth listen-before-talk procedure maycomprise a sixth listen-before-talk procedure. According to an exampleembodiment, the wireless device may perform the sixth listen-before-talkprocedure at a fifth time. According to an example embodiment, thewireless device may determine the fifth time based on the second backofftime interval. According to an example embodiment, the wireless devicemay perform the listen-before-talk procedure on the second sub-bandbased on the second backoff time interval being shorter than the firstbackoff time interval. According to an example embodiment, the wirelessdevice transmit at least one preamble via the second sub-band based onthe listen-before-talk procedure indicating the second sub-band clear.

According to an example embodiment, a wireless device may transmit, fora random access procedure, a first preamble via a bandwidth part. Thebandwidth part may comprise a first sub-band and a second sub-band.According to an example embodiment, the wireless device may receive arandom access response. The random access response may indicate a firstbackoff indicator of the first sub-band. The random access response mayindicate a second backoff indicator of the second sub-band. According toan example embodiment, the wireless device may determine a preambleretransmission for the random access procedure. The wireless device maytransmit a second preamble via the second sub-band. According to anexample embodiment, the wireless device transmit the second preamblebased on a second listen-before-talk procedure indicating the secondsub-band clear. According to an example embodiment, the wireless devicemay perform the second listen-before-talk before a first time instancedetermined by the first backoff indicator. According to an exampleembodiment, the wireless device may perform the secondlisten-before-talk after a second time instance determined by the secondbackoff indicator.

According to an example embodiment, a wireless device may transmit, fora random access procedure, a first preamble via a bandwidth part. Thebandwidth part may comprise a first sub-band and a second sub-band. Thewireless device may receive a random access response. The random accessresponse may indicate a first backoff indicator of the first sub-band.The wireless device may determine a preamble retransmission for therandom access procedure. The wireless device may transmit a secondpreamble via the first sub-band. According to an example embodiment, thewireless device may transmit the second preamble based on a firstlisten-before-talk procedure. According to an example embodiment, thewireless device may perform the first listen-before-talk procedure basedon the determining with a delay. The wireless device may determine thedelay based on the first backoff indicator. According to an exampleembodiment, the first listen-before-talk procedure may indicate thefirst sub-band clear. According to an example embodiment, the wirelessdevice may transmit the second preamble based on one or more secondlisten-before-talk procedures. According to an example embodiment, thewireless device may perform the one or more second listen-before-talkprocedure indicating the second sub-band occupied;

According to an example embodiment, a base station may receive, for arandom access procedure, a first preamble via a cell. According to anexample embodiment, the cell may comprise a first sub-band and a secondsub-band. The base station may transmit a random access response. Therandom access response may indicate a first backoff indicator. Accordingto an example embodiment, a first backoff time interval of the firstsub-band may be determined based on the first backoff indicator. Therandom access response may indicate a second backoff indicator. Thesecond backoff time interval of the second sub-band may be determinedbased on the second backoff indicator. According to an exampleembodiment, the base station may receive, at a first time, a secondpreamble as a preamble retransmission for the random access procedure.According to an example embodiment, the first time may be determinedbased on a backoff time interval that is a shorter one of the firstbackoff time interval and the second backoff time interval.

In this disclosure, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” Similarly, any termthat ends with the suffix “(s)” is to be interpreted as “at least one”and “one or more.” In this disclosure, the term “may” is to beinterpreted as “may, for example.” In other words, the term “may” isindicative that the phrase following the term “may” is an example of oneof a multitude of suitable possibilities that may, or may not, beemployed to one or more of the various embodiments.

If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on”(or equally “based at least on”) is indicative that the phrase followingthe term “based on” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “in response to” (or equally “inresponse at least to”) is indicative that the phrase following thephrase “in response to” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “depending on” (or equally “depending atleast to”) is indicative that the phrase following the phrase “dependingon” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.The phrase “employing/using” (or equally “employing/using at least”) isindicative that the phrase following the phrase “employing/using” is anexample of one of a multitude of suitable possibilities that may, or maynot, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics ormay be used to implement certain actions in the device, whether thedevice is in an operational or non-operational state

In this disclosure, various embodiments are disclosed. Limitations,features, and/or elements from the disclosed example embodiments may becombined to create further embodiments within the scope of thedisclosure.

In this disclosure, parameters (or equally called, fields, orInformation elements: IEs) may comprise one or more information objects,and an information object may comprise one or more other objects. Forexample, if parameter (IE) N comprises parameter (IE) M, and parameter(IE) M comprises parameter (IE) K, and parameter (IE) K comprisesparameter (information element) J. Then, for example, N comprises K, andN comprises J. In an example embodiment, when one or more (or at leastone) message(s) comprise a plurality of parameters, it implies that aparameter in the plurality of parameters is in at least one of the oneor more messages, but does not have to be in each of the one or moremessages. In an example embodiment, when one or more (or at least one)message(s) indicate a value, event and/or condition, it implies that thevalue, event and/or condition is indicated by at least one of the one ormore messages, but does not have to be indicated by each of the one ormore messages.

Furthermore, many features presented above are described as beingoptional through the use of “may” or the use of parentheses. For thesake of brevity and legibility, the present disclosure does notexplicitly recite each and every permutation that may be obtained bychoosing from the set of optional features. However, the presentdisclosure is to be interpreted as explicitly disclosing all suchpermutations. For example, a system described as having three optionalfeatures may be embodied in seven different ways, namely with just oneof the three possible features, with any two of the three possiblefeatures or with all three of the three possible features.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an element thatperforms a defined function and has a defined interface to otherelements. The modules described in this disclosure may be implemented inhardware, software in combination with hardware, firmware, wetware (i.e.hardware with a biological element) or a combination thereof, all ofwhich may be behaviorally equivalent. For example, modules may beimplemented as a software routine written in a computer languageconfigured to be executed by a hardware machine (such as C, C++,Fortran, Java, Basic, Matlab or the like) or a modeling/simulationprogram such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript.Additionally, it may be possible to implement modules using physicalhardware that incorporates discrete or programmable analog, digitaland/or quantum hardware. Examples of programmable hardware comprise:computers, microcontrollers, microprocessors, application-specificintegrated circuits (ASICs); field programmable gate arrays (FPGAs); andcomplex programmable logic devices (CPLDs). Computers, microcontrollersand microprocessors are programmed using languages such as assembly, C,C++ or the like. FPGAs, ASICs and CPLDs are often programmed usinghardware description languages (HDL) such as VHSIC hardware descriptionlanguage (VHDL) or Verilog that configure connections between internalhardware modules with lesser functionality on a programmable device. Theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the scope. In fact, after reading the abovedescription, it will be apparent to one skilled in the relevant art(s)how to implement alternative embodiments. Thus, the present embodimentsshould not be limited by any of the above described exemplaryembodiments.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112. Claims that do not expressly include the phrase “means for”or “step for” are not to be interpreted under 35 U.S.C. 112.

What is claimed is:
 1. A method comprising: transmitting, by a wirelessdevice and for a random access procedure, a first preamble via a cellcomprising a first sub-band and a second sub-band; receiving a randomaccess response indicating: a first backoff indicator indicating a firstbackoff time interval of the first sub-band; and a second backoffindicator indicating a second backoff time interval of the secondsub-band; determining a preamble retransmission for the random accessprocedure; selecting, as a backoff time interval, a shorter one of thefirst backoff time interval and the second backoff time interval; andperforming, at a time based on the backoff time interval, alisten-before-talk procedure.
 2. The method of claim 1, wherein thelisten-before-talk procedure is performed on the first sub-band inresponse to the first backoff time interval being shorter than thesecond backoff time interval.
 3. The method of claim 2, furthercomprising transmitting a second preamble via the first sub-band basedon the listen-before-talk procedure indicating that the first sub-bandis clear.
 4. The method of claim 2, further comprising performing, at asecond time based on the second backoff time interval, a secondlisten-before-talk procedure on the second sub-band based on thelisten-before-talk procedure indicating that the first sub-band isoccupied.
 5. The method of claim 4, further comprising transmitting athird preamble via the second sub-band in response to the secondlisten-before-talk procedure indicating the second sub-band is clear. 6.The method of claim 5, wherein there is no random access channeloccasion on the first sub-band between the time and the second time. 7.The method of claim 5, wherein there is at least one random accesschannel occasion on the first sub-band between the time and the secondtime.
 8. The method of claim 7, further comprising performing, for theat least one random access channel occasion, at least one thirdlisten-before-talk procedure on the first sub-band, wherein the at leastone third listen-before-talk procedure indicates the first sub-band isoccupied.
 9. The method of claim 1, further comprising transmitting afourth preamble via the first sub-band in response to a fourthlisten-before-talk procedure indicating the first sub-band is clear, thefourth listen-before-talk procedure performed at a third time on thefirst sub-band after the listen-before-talk procedure indicating thefirst sub-band is occupied.
 10. The method of claim 9, wherein there isno random access channel occasion on the second sub-band between thetime and the third time.
 11. A wireless device comprising one or moreprocessors and memory storing instructions that, when executed by theone or more processors, cause the wireless device to: transmit, for arandom access procedure, a first preamble via a cell comprising a firstsub-band and a second sub-band; receive a random access responseindicating: a first backoff indicator indicating a first backoff timeinterval of the first sub-band; and a second backoff indicatorindicating a second backoff time interval of the second sub-band;determine a preamble retransmission for the random access procedure;select, as a backoff time interval, a shorter one of the first backofftime interval and the second backoff time interval; and perform, at atime based on the backoff time interval, a listen-before-talk procedure.12. The wireless device of claim 11, wherein the listen-before-talkprocedure is performed on the first sub-band in response to the firstbackoff time interval being shorter than the second backoff timeinterval.
 13. The wireless device of claim 12, wherein the instructionsfurther cause the wireless device to transmit a second preamble via thefirst sub-band based on the listen-before-talk procedure indicating thatthe first sub-band is clear.
 14. The wireless device of claim 12,wherein the instructions further cause the wireless device to perform,at a second time based on the second backoff time interval, a secondlisten-before-talk procedure on the second sub-band based on thelisten-before-talk procedure indicating that the first sub-band isoccupied.
 15. The wireless device of claim 14, wherein the instructionsfurther cause the wireless device to transmit a third preamble via thesecond sub-band in response to the second listen-before-talk procedureindicating the second sub-band is clear.
 16. The wireless device ofclaim 15, wherein there is no random access channel occasion on thefirst sub-band between the time and the second time.
 17. The wirelessdevice of claim 15, wherein there is at least one random access channeloccasion on the first sub-band between the time and the second time. 18.The wireless device of claim 17, wherein the instructions further causethe wireless device to perform, for the at least one random accesschannel occasion, at least one third listen-before-talk procedure on thefirst sub-band, wherein the at least one third listen-before-talkprocedure indicates the first sub-band is occupied.
 19. The wirelessdevice of claim 11, wherein the instructions further cause the wirelessdevice to transmit a fourth preamble via the first sub-band in responseto a fourth listen-before-talk procedure indicating the first sub-bandis clear, the fourth listen-before-talk procedure performed on the firstsub-band after the listen-before-talk procedure indicating the firstsub-band is occupied.
 20. A base station and a wireless device, wherein:the base station comprises one or more processors of the base stationand memory storing instructions of the base station that, when executedby the one or more processors of the base station, cause the basestation to: receive, for a random access procedure, a first preamble viaa cell comprising a first sub-band and a second sub-band; and transmit arandom access response indicating: a first backoff indicator indicatinga first backoff time interval of the first sub-band; and a secondbackoff indicator indicating a second backoff time interval of thesecond sub-band; and the wireless device comprises one or moreprocessors of the wireless device and memory storing instructions of thewireless device that, when executed by the one or more processors of thewireless device, cause the wireless device to: transmit the firstpreamble; receive the random access response; determine a preambleretransmission for the random access procedure; select, as a backofftime interval, a shorter one of the first backoff time interval and thesecond backoff time interval; and perform, at a time based on thebackoff time interval, a listen-before-talk procedure.